To put it simply, StumbleUpon shows the "stumbler" all the internet's cool shit--and there is much cool shit which is on said internet.

The New York Times likes it too:

Anyway, on Friday I was stumbling, and found a website with all these different wallpapers. Not the decorative paper you put on your walls to make a room less bland, but rather that which occupies one's desktop on their computer (the background). Friday, I was coming off being sick (I was told to blog about that, but I'd rather not) along with the rest of my family who are 82.9 miles away, and I found a website with wallpapers. I sat in my bed, completely expressionless, for five hours straight, finding wallpapers and copying them into a folder on my desktop. They are mostly sweet photos (cities at night, nature scenes, artsy black and white shit, etc), or adobe influenced/made abstract art. I spent another three hours looking last night whilst video chatting with a friend. I found a bunch of backgrounds. This is my favorite:

Your moment of zazen.
Joel: Sounds good. I could go for some kitch.
Aaron: Super delish.
Joel: Maybe I'll get some jim.
Aaron: That's a socially acceptable alternative to kitch.
"I once saw a forklift lift a crate of forks. It was way too literal for me." --Mitch Hedberg