When it comes to making free calls across the internet using Voice over IP technology, Skype is certainly leading the pack. With almost 26 million people having downloaded the software, Skype is the most used free internet application.

Developed by the people behind the file-sharing service Kazaa, Skype offers free internet telephony with another PC user as long as both have the Skype software.

If you're an existing Skype user, the first thing you'll notice is that the interface has had a makeover. Another key addition is the use of public chats, so you can now start a conversation between a group of people, whether you know those people or they're random users who happen to join your topic of conversation.

The latest version of Skype contains improvements to the call quality, including reducing background noise, delay, fewer call drops, fewer cut-outs and so on. If you change your microphone, Skype will now automatically detect and alter your preferences.