Del.icio.us

This ones actually pretty cool. you can pretty much collect links to all the stuff you like from all over the internet. It has a social-media site feel to it, because you can brows links other people have liked and shared, as well as connect with people who like the same stuff as you via your links.  Additionally it could prove helpful for keeping track of all the random sites and information you find on a web. ever found a site, left it, then completely forget what it was/how to get to it? problem solved.