1. Google: Internet is just not the same without its search and map engines. 2. YouTube: No need for a cable TV subscription. 3. Wikipedia: Useful site to look things up in a hurry, especially articles relevant to academic subjects. 4. Dictionary (also Thesarus): Similar to Wikipedia, but when just looking up words. 5. Deviantart.
1) deviantArt (This website of course!)
2) IGN
3) Facebook