Dungeon Grind (http://dungeongrind.co.uk/archive/prelude-i/)
Showcasing the trials and tribulations of the denizens of Castle Evilgrim in the face of rabid adventurers constantly trying to kill them and take their stuff.
Looking for Group ( http://www.lfgcomic.com/page/1/ )
Telling the tales of a very unlikely band of adventurers. I actually discovered this second one through a couple of youtube videos.
The first video is "Slaughter Your World," a parody of The Little Mermaid song "Part of Your World" (you probably don't want the kids to watch this one).
The second video is "This is War," a parody of the Aladdin song "A Whole New World" (slightly less gruesome than the first, IMO, but not by much).
If anyone knows of some other good fantasy webcomics, do share!