I haven't really read any comics since I started playing WoW, but a few that I was religiously into were:

www.leasticoulddo.com
www.bobandgeorge.com
www.somethingpositive.net
www.megatokyo.com
www.reallifecomics.com
www.nuklearpower.com
www.sinfest.net
www.machall.com
www.penny-arcade.com
www.go-girly.com (Rated R, so you know, for nudity, being sexually explicit, and for lesbianism)
www.manatheater.com
Sexylosers.com, which I won't povide a quick-link for because of its sexually graphic and questionable nature. If you're that interested, type it in. But have a vomit-bucket ready for a few of the strips.