http://www.stumbleupon.com/ http://www.digg.com/ Both can drive a good amount of traffic -- IF THE WEB PAGES YOU SUBMIT ARE EXTREMELY INTERESTING TO THE StumbleUpon and Digg members.
stumble & digg are not money makers, but traffic makers (if everything goes well). Basically anybody can submit any website to digg (or stumble - or delicious, reddit - there are lots of them) and then users will cast votes to stories. The most popular stories will be seen on the front page of digg.com. That way people who visit digg.com might see your site, and visit it. Just search for "social bookmarking" for more information - there's plenty of available here on these forums.