REFERENCE
MAKEUP ALLEY: If you're thinking about buying a certain shade of Lip Glass or are in dire need of a new brand of blush, but don't feel like wasting a ridiculous amount of money on a shitty product, this site will definitely save your ass.
YAHOO ANSWERS: If you have a question to ask, there's a definite likelihood that at some point it's already been asked and answered. So do a little idiot-proof research before you bother boring someone to death. Seriously.
URBAN DICTIONARY: For those times when your friends are using phrases completely foreign to you and you've been pretending to know what they're talking about. I bet my friends use this a lot ;]
NETWORKING
FACEBOOK : Well, duh. If you're not on there yet, you've fallen far too behind in your internet dealings. Sign up, already.
43 THINGS : Add things you want to do to your list of 43, update the status of each task, etc. Use the same login to access their sibling sites
43 People,
43 Places,
All Consuming, and
Lists of Bests.
FLIXSTER : Sign up and add your favorite movies, actors, directors, etc. Write and read film reviews, change your profile skin, take movie quizzes or write your own. It's basically a movie buff's paradise.
GAMING
EVERYVIDEOGAME.NET : Just as the title would more than likely suggest, it has pretty much every freakin' videogame from old consoles online for you to play. For free!
NEOPETS : All of the cool kids had one of these at some point in time. There are plenty of things to keep you occupied, including a large assortment of random games that let you earn NEOPOINTS! I'm particularly infatuated with playing Kuo-Jong and Destruct-O-Match in the Puzzles section.