I avoid associating my real identity with anything on the internet, even if it's a private account. I only do it where I have to, like for banking. I don't take many steps to be untraceable (just Ghostery and a variety of usernames), but my reasons are twofold: I have read too many stories about people getting screwed for something they did or said online. Jobs losts, relationships destroyed, and often due to misunderstandings. I sometimes forget that The Internet is Serious Business, and say things that I would normally only say around close friends, things I might not want everyone to know. Secondly, I am a private person and I don't take much pleasure in being congratulated or showered with attention, so in cases where I do make valuable contributions, I am happy to do so pseudonymously or anonymously.

Then again, I've met people from the internet in real life, in both friendly and professional contexts, with no issues thus far. When I want to chat with someone, I send them an email or IM username, which both have my actual name and location on. I'm much more comfortable with it 1-on-1 than in the open crowd of 3 billion internet users.