This one (answers.com) is one; then, there are lots of wikis and discussion groups. For example, you can contribute to Wikipedia. You can also search for discussion groups in any area that interests you.
KandeCorn.Piczo.Com
bungie.net?
gracieandranda.webs.com
tracpeople.moonfruit.com tycanyon.moonfruit.com
Coolmath.net
There are many "Cool" virtual game sites.
http://www.teenchat.com/
didgi draw on crayola.com
Daily booth
Dragon world . Com
cool math.com farm five.com addicting games.com whack your ex.com
Whatever your interests or hobbies are, go to Google.com and in the search box type "my interests are ____" and you will find some interesting and cool websites. Everyone has different interests and even websites on the same subjects, you make like one and not the other.