hell, i read Order of the stick, but i have never played D&D. closest i came to it, is when we picked random phrases from an old D&D book(we got from the free store), and used them as lyrics for our drunken jamming.
penny arcade is great, the old archived stuff is kind of lame though. much smarter than most.
Ctrlaltdel is pretty good too. really clean drawing style, some sort of story, and frequently has really hilarious stuff. not always though.
VGcats, probably the funniest of the "gamer" comics, nearly everyone is immensely funny, but the guy never NEVER updates.
Looking for Group is okay as well. some of the WOW referencing and plot stuff is super lame, but the one character Richard is sweet enough to read for. besides, fairly small archive, doesnt take long to catch up on.
XKCD is probably one of the funniest, smartest ones out there. dont expect to get all the jokes though.
obviously QC is awesome. period.
Dr McNinja, is one of my new favourites. twisted, hilarious, some plot, ridiculous scenarios, ninjas, its got everything.
and Something Positive. i just finished reading the archive. holy crap, took me like 8 times as long as the Q archive. really funny though. lots of great characters, decent drawing, offensive humour. some of the storylines are incredibly sad though.
plus the best ever small comedic sidekick! sorry pintsize, but you arent a cute boneless pink cat like choochoobear.