ZyXEL's ZyWall 35 shows that, while small in dimensions, it is not small on features. The front panel of the appliance houses two WAN and four LAN Fast Ethernet ports, while the rear of the device has out-of-band management through it is console port and a PC Card slot, so you can add 802.11g WiFi (see company website for supported cards).
At the small or home office end of the market we have the ZyWall 100 Internet Security Gateway. When we looked at the ZyWall 50 appliance in the VPN Group Test last year, we had a few concerns, such as build quality. This issue has clearly been addressed, since the ZyWall 100 is a robust yet compact device with a simple and attractive design.