There's also:
Irregular Webcomic: (story driven, lots of science and math jokes, but a lot of it is funny outside of that)
Legostar Galactica: (Parody of Star Trek, Battlestar Galactica, Star Wars, Dr Who, and various other nerdy sci-fi things)
Darth and Droids /
DM of the Rings: (only funny if you know Dungeons and Dragons, or if you like Star Wars/ Lord of the Rings)
The Order of the Stick is really funny, and enough of the jokes are about things that aren't D&D related for anyone to understand it.
Quitting Time: (the humor is mostly about the lame or annoying aspects of working jobs like retail, so anyone can laugh at it! YAY!!!)