I envy you. I started reading around #150. About 18 years ago? I don't know. You're in for something nice. Check Alice Grove too, and Dresden Codak, Dinosaur Comics, and some other things that might be not to your liking so I won't mention them. Also try smbc and xkcd (Randall's) and that other one I can't remember the name of -- now that's bugging me.
EDIT: meh, I'll think of it tomorrow: I've already thought of half a dozen, and I don't want you to get on more of a binge.
EDIT2: The Perry Bible Fellowship.