Symantec's Gateway Security 5460 is the largest, and one of the most powerful, appliances that we have had on test. It has eight Gigabit Ethernet ports, which can be configured to segregate a network or for high availability. The firewall can also be configured to load balance between a cluster, improving performance provided you have the correct license.
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).