I've used all of the popular bookmarking websites like reddit, digg, etc. But what sets StumbleUpon apart from the rest, is that you get instant "hits" every time you stumble an article of your own. For example...When I stumble my fresh article...I hop over to my google analytics (in "real-time beta") to see that 4 or 5 "hits" are coming from San Francisco (their headquarters i'm guessing?). which is fine with me. now if we could compile a list of websites like this, I'm sure it would make for faster indexing, and rankings. Anyone else notice this? and have a list of websites that operate in this fashion; the same way StumbleUpon does?