I deactivated (which doesn't mean delete, see '2504 steps to closing your Facebook account') my (largely unused) Facebook account and deleted all cookies on my browser. I also changed all my passwords. I'm looking into setting up my own site on a server I can reasonably trust and hook it up with an email address so I can get out of Google's clammy embrace. Finally I will carefully monitor the sites I'm registered at and make sure any info I share is not too sensitive. Despite my efforts a number of large companies, governmental organistions (guess who) and anonymous data hackers very probably have a lot more information on me than I can imagine. With data mining programs getting more powerful, Bush still in office, privacy issues being brushed off as anti-progressive and most users still happily accepting the unbelievable terms of service drawn up by the social networking giants, it's very easy to compile a profile on anyone who spends more than average time on the Internet. Do you know Google doesn't even have an email address you can complain to? You have to join a forum and get other users to help you! Facebook controls every bloody step you take, giving you wise advice at every corner ('you want to deactivate your account because it's not useful? try using some more of our features and get some more friends..'!!).
In Wired words: 'If we want an open social web, we're going to have to build it ourselves, using technologies that no one company controls.'