Hijinks Ensue is one of my favorite web comics. It has quickly replaced xkcd as my online comic strip of choice. While xkcd is very funny, many of the jokes are WAY inside, seemingly designed for engineers and science students. I can appreciate that, but I don’t really want to have to go to wikipedia after reading a comic strip.
Hijinks Ensue is nerdy, too, but more consistently funny as it focuses on the fanboy aspect of geek culture and not the actual possession of geeky knowledge.