Did you mean social networking? If so, for me it's:
1. Facebook - open almost all the time when I'm online
2. LiveJournal - read daily, post weekly or more often
3. YouTube - regularly watch, less often sharing
4. Flickr - image uploading/sharing
5. LinkedIn - business, maybe post or visit 1-2 times a month
I also more rarely use Pinterest (I have little spats of liking/repinning then forget it for weeks/months), Meetup, and CrunchyRoll (only for viewing, never for the social stuff).
(I'm a web developer, so I follow the strict meaning of "social networking" which precludes personally hosted/individual blogs and forums. A site must have specific features to be a social networking site, so while LiveJournal is one, WordPress and Blogger are not).