I recently came across a neat site called StumbleUpon. It's basically a tool that you download, which adds a Stumble toolbar to your web browser. Any time you get bored, you can click the Stumble button and it'll take you to a random site that falls into your interest categories. You can rate sites (its a binary rating system; either you like the site or you don't) and this will help StumbleUpon further refine the types of sites it sends you to. You can submit new sites you come across to StumbleUpon by rating them (and in a fit of shameless self-promotion, I submitted my blog).
It's kinda fun and I've found some interesting sites through it. Check it out.