StumbleUpon lets you "channelsurf" the best-reviewed sites on the web. It is a collaborative surfing tool for browsing, reviewing and sharing great sites with like-minded people. This helps you find interesting webpages you wouldn't think to search for.

Channel surf the internet for great websites, videos, pictures, games and more!
Get personalized recommendations according to your interests
Rate, review and share what you find
Keep an online history of the things you've Stumbled
No adware or spyware guaranteed