Qwantz: http://www.qwantz.com/
Sam and Fuzzy: http://www.samandfuzzy.com/
Dr. Mcninja: http://drmcninja.com/index.html
Whispered Apologies (Run by same people who do Qwantz): http://www.qwantz.com/apologies/
Another comic, that's been completed but is really good IMO is Kidd Radd: http://home.att.net/~miller.daniel.r/