A website at stripcreator.com that allows its users to create three-panel comic strips using a predefined set of characters. Backgrounds and characters come from Chopping Block, Diesel Sweeties, Explodingdog, Fat Jesus, Goats, Jerkcity, Penny Arcade (and Ko Fight Club), and When I Grow Up.
The most common themes for strips seem to be Pop Culture, Religion, and the Personal Lives of its users. Personally, I find the third category the most interesting, as when I come across some person I've never met's one-sided version of something one of his friends said or did.
While the fact that the site's users are not quite professionals does show occasionally, some of the more prolific users are actually quite funny.
siouxsie mentioned that Stripcreator is run by Brad Turcotte, a/k/a Brad Sucks.