As a major fan of D&D, my favorite webcomics also fall into that sort of playstyle:
The Order of the Stick:
www.giantitp.com - This comic is the longest comic I've followed. It's been around for years, and the humor continues to interest me.
Erfworld:
www.erfworld.com - Though very fresh, Erfworld is by far the most promising webcomic I've come across. It has a fantastic sense of humor, every page is absolutely crammed with detail and quirky references to the real world, and it's a comic I recommend everyone read.
I also have been following a great prohibition-era comic strip which replaced humans with feline characters -
Lackadaisy:
www.lackadaisycats.com
