The thing about humor is that it's so often in the eye of the beholder, particularly when it comes to geek humor. Lots of inside jokes abound on the internet, and unless you're in the know because you're part of a particular fandom, or you're aware of certain memes or whatever, a lot of jokes can fall flat.
That being said, there's a fair number of places I go through the week to find me a little something to laugh about, so I'll start with there.
Not even remotely safe for work. At all. But full of odd sexual fantasy humor that makes it particularly amusing for the D&D set. It updates every Sunday.
Also not really safe for work sometimes, but tends to have some excellent satire, particularly about things in the news right this moment...or sometimes it's about that motherfucking pterodactyl.
3) Hyperbole and a Half
You've probably seen that particular image if you've been on the internet anytime in the last few years or so - it's spawned a million tumblr memes alone.
Still funny, though.
4) The Bloggess
Jenny is crazy. And awesome. And has a book coming out this month full of her crazy and awesomeness. (And she gets to chat with Wil Wheaton. And Neil Gaimen. And Amanda Palmer and Felicia Day and wow am I jealous.)
I usually have Tumblr up all damn day. And I laugh a lot more than I used to. And this is a good thing.