If you want a small factor board then Shuttle is the king of that. Your 2 choices are...
If you just have to have a AGP slot for video then look at the MK32N. It has sound, ethernet, video, and a AGP slot. It is a mAtx board. KM266 chipset.
If you just need a computer to play basic games or non, then look at the FS40. It has sound(5.1ch), video, ethernet, Firewire, and TV output. It is a Flex ATX board, VERY Small. SiS740 chipset.
The KM266 has a AGP port and ok on-board video. The SiS740 has no AGP slot but the video is a lot better, like a low end GF2 MX card type level.