I quite like xkcd (xkcd_rss). OK, not every one is funny, but there are some real gems.

It appears these people (xkcdsucks) doesn't share that opinion though amd are willing to write a post criticising each cartoon when they are released.

I think the tagline says it all really:

"[a] vitriolic and bitter collection of unwarranted nastiness about a silly and harmless comic."