I have a few that I really like:
Looking for Group- very loosely based on World of Warcraft. About an undead warlock and an elf traveling together, it's Hilarious!
Twokinds- takes place in a world with several non-human races, with whom the humans are at war. The story begins with a human with amnesia who finds a keidran, one of the non-human races. A good story, it gets better as it goes on.
Order of the Stick- will be funnier if you are familiar with the tabletop game Dungeons and Dragons, but is funny nonetheless. It's about a team of adventurers trying to destroy an evil undead sorcerer.
Housepets!- follows the life of a sentient cat and dog who are, as the name of the comic suggests, housepets. It is an amusing comic that hints at plot lines lurking in the background.