Shaun Nichols: So there's a ton of misinformation and outright fiction regarding nanotechnology in popular culture, but that doesn't mean that there isn't the possibility for nefarious uses.
Any time you can build complex structures on such a tiny scale, you raise the possibility for danger. Now it may not be in the form of invisible nano-viruses controlled by supercomputers. But even the miniaturisation of computers made possible by nanotech could lead to new concerns over things like privacy.
Nanotechnology is a very important scientific development with almost limitless possibilities to improve life. But as has been the theme for this entire list, things that improve life can also add new dangers to it.
Iain Thomson: With every great advance comes pitfalls. When the first atomic bomb was being developed a small group of those in the project were worried that the reaction might ignite the atmosphere, and while the science said this was unlikely it wasn't decided until the first test.
Nanotechnology is a massively important technology. It promises to give us the ability to manipulate individual atoms, making a host of new materials, medicines and computing technologies possible. Without it humanity would be limiting itself too greatly, but that doesn't mean all risks should be taken without thought.
But my fear for this technology isn't the present day - it's 50 or 100 years down the line. Once nanotech becomes commonplace who knows what some nutjob is going to cook up in their basement.
4. Surveillance equipment
Iain Thomson: Before moving to San Francisco I lived in London, the most heavily CCTVed city on the planet. Standing outside the office I could see eight cameras, all of which were capable of videoing me and one of which had a directional microphone.
Orwell had it wrong, we don't have Big Brother in the house. Instead it's out on the street and your home is your only castle, for the moment at least. Surveillance technology is useless for stopping crime, despite what we're told, although it can be of use at catching people after the act. But am I the only one who is worried about this development?
In days gone by we had the best surveillance technology in the world - the neighbours. For eleven years I lived in one of the roughest areas of London and had no fear of burglars because I knew the grandmother living across the street sat at her front window all day and she could spot a "wrong 'un" at fifty paces. Sadly now we put out trust in technology, not our friends.
We should also consider who is watching these cameras. Sitting on your backside all day as a professional voyeur is hardly a skilled job and the police seldom do it, it's left down to poorly paid contractors who have every reason to abuse the system. Frankly I don't trust these people further than I can throw them and it's about time we worked on bringing collective responsibility back to society rather than entrusting it to technology.
Shaun Nichols: Perhaps it's because I've never lived outside the states, but large-scale surveillance really gives me the creeps. For surveillance systems to work, people have to constantly trust whoever is on the other end of the camera, and few people trust the government to that extent. Who knows the person watching that footage and what they are doing?
Don't get me wrong, camera systems can be very good for collecting evidence of things such as drug dealing hotspots, but they're not particularly useful for most crimes. In a city of several million people, what chance do the police have of catching the guy who mugged me when they look at the video hours later?
I think everyone would be safer and happier if most of the money spent on installing and maintaining these surveillance systems was instead used to put a few more cops on the beat.
3. Digital Rights Management (DRM)
Shaun Nichols: Many of the dangers we suggested on this list thus far have been hypothetical. But with DRM software we've already seen the dangers and some of the problems they can cause.
Let me start by saying that publishers do a have a right to stop the theft of their products through piracy and unauthorised redistribution.
The problem is that the companies have gone way too far with the idea and seemingly come to the belief that purchasing digital content constitutes waiving one's right to privacy. When DRM software starts doing things such as archiving my system information and sending it to an external server, I get upset, and I believe rightfully so.
The best example of this was the Sony rootkit case. The company became so paranoid about users sharing songs that they went as far as to load the disks with software that covertly and illegally installed programs on customers' systems.
Fortunately, this is beginning to go away. After years of insisting that DRM was absolutely necessary, publishers are finally starting to listen to their customers and cut back on or completely eliminate many DRM components.
Iain Thomson: Back when Shaun was still dealing with toilet training DRM showed its ugly side - the Brain virus.
This was an attempt to stop the piracy of a medical software package that turned into a virus that knackered computers across the world. Sadly, big media hasn't learnt that lesson.
Shaun rightly highlights the Sony rootkit case. What was so disturbing about that incident wasn't the software itself but the apparent arrogance of Sony in presuming that its rights to protect intellectual property were more important than the safety of yours and my computers. This lesson hasn't been learned, if the current ACTA treaty is anything to go by.
What makes it worse is that DRM is largely useless. Media companies can hire a handful of people to design code that will protect their copyright. But there's an army of people out there who will devote hours, days, even years, to defeating it just on principle. Sooner or later this arms race will be lost by DRM, but I fear a lot of computers are going to be messed up in the meantime.
Iain Thomson: When Shaun and I were coming up with ideas for the weekly Top 10 the topic of dangerous technologies came up and it hit a spark. I sat there thinking 'Windows', and the fact this isn't number one is down to his winning a spirited argument and having logic on his side.
On one level Windows spawned the computer's acceptance by business. Having one standard to work to let developers build applications that everyone would use and made computing a safe choice for the IT buyer.
But, as we've seen from agriculture, monocultures are useful in the short term but can be incredibly damaging at the end of the day. Having Windows on 95 per cent of computers a few years ago meant that malware writers had a big, fat bullseye to aim at and ultimately helped spawn the online fraud industry that is making everyone's lives a misery.
It's not that Windows is bad code, although it has been and still has serious weaknesses. It's that having one standard to rule them all is very bad security practice. Apple makes much of the fact it doesn't get viruses but that's got more to do with it being a smaller target. Personally, I'm sticking with Linux until it gets to be such a big target that we get malware problems there, then BeOS gets a turn if it's still up to date thanks to volunteers.
It is possible to make Windows secure, but it takes a hell of a lot of work and most IT managers have enough problems on their hands to make locking down corporate networks next to impossible.
Shaun Nichols: Windows in and of itself is a huge security liability, and while some of it is Microsoft's fault, not all of it is.
First and foremost, the company by all accounts got serious about security way too late in the game. The seems to have had a very positive effect on securing Windows, but it only came after the flood gates had been opened for several years and tens of millions of users were left at risk.
As Windows XP transitions into Windows 7, the new security practices should become even more apparent, but with malware now becoming such a lucrative industry, the attacks will also become more sophisticated.
There are also factors beyond Microsoft's control that make Windows dangerous. The sheer number of unpatched and poorly maintained computers in the world is more than enough to keep all of the world's botnet herders knee deep in victims for years. Sometimes users are too lazy to install monthly updates, other times they are using pirated copies of the software that can't be updated. Regardless, the amount of 'low-hanging fruit' out there is what keeps much of the malware industry thriving.
This does not mean that Mac and Linux users should ignore security, however. Just because you're not the prime target for infection doesn't mean that people still aren't targeting your system.
Shaun Nichols: Many of our technologies on this list have very legitimate and highly useful purposes. I can't however, think of too many legitimate uses for computer code that can automatically install and replicate itself on a system without any user knowledge or interaction.
Initially developed as a bit of a curiosity or joke, computer viruses (and worms) have become a primary threat to IT worldwide and their eradication has spawned a multi-billion dollar industry.
Up until the internet boom, viruses were primarily just a threat to the surrounding software; the worst that could happen was that a destructive virus could wipe out your system. Now, this meant the possible loss of huge amounts of data, but the only worry was destruction.
Over the last decade or so, however, malicious programs have gone from destructive to larcenous. Losing your system can be pretty bad, but it's nothing compared to having your bank account wiped clean or your credit card stolen.
Iain Thomson: I kind of miss the old days, when viruses were done for bragging rights on message boards. Now organised crime has got in the game and things have become so much worse.
Viruses have the potential to screw up the computing model in two key ways. Firstly, as Shaun has mentioned, they can destroy vast amounts of data. This has become worse through the interconnected nature of computers.
But secondly viruses damage confidence. Ecommerce is going to become an ever increasing part of the global economic system but fear of infection is stifling that. Already people are being turned off online banking and shopping because of the fear of getting their credit rating junked by a phisher. This is going to get worse before it gets better.
Law enforcement used to love the old-style virus writers. They weren't profit-motivated and once caught coughed up everything for fear of going to jail. Now we face distributed teams of highly motivated criminals who bring to computer crime the same level of criminal nastiness as you see in armed robbery, mugging and murder.
The battle against viruses will never end, barring a major advance in technology or users getting much smarter. To quote Winston Churchill "This is not the end. It is not even the beginning of the end. But it is, perhaps, the end of the beginning."