I've never claimed that I don't have a nerdy side. I've also never claimed to be on the cutting edge of what's new and hip on the 'net. Keeping those two statements in mind, I want to share a sweet "new" site I've run across. "New" is in quotes, because I'm sure everyone, but me, has been using StumbleUpon since the late-90s. If, however, you haven't heard of it, let me tell you... it's fun and very addictive.
First of all, I can't make any claims about the site's security. So use it at your own risk. Like many social networking sites, it's full of good and bad stuff. Use good surfing habits while visiting. From a technical perspective (and security perspective) I would suggest that you just use the web version and don't download the toolbar.
With that said, let me tell you a little bit about the site. StumbleUpon is a much less formal method for finding the kinds of things you enjoy surfing on the web. Instead of having to enter keywords, sites related to a particular subject (photos for example) are presented to the user. After visiting a site, you use the web toolbar to "rate" it. From these ratings, and the ratings coming from other users, StumbleUpon builds a profile of your likes and dislikes and picks out other sites that you might enjoy. The more you use it, the more accurate its predictions become. Each time you visit, you get a new list of cool stuff to enjoy.
Right now, the site is free to use. Again, use your good internet surfing safety, and have fun. StumbleUpon is quickly becoming one of my new favorite time wasters!