People opt out of the online world all the time. Except, what to do with all that content that is out there. here is one solution: Suicide Machine.
Here is a good article from the LA Times.
Want some good advise? Never, not ever, place anything online that you don't want to see published, on a job interview, or in your school paper. People have lost jobs because they thought that they were in a private room when commenting online. Hey, online there is no privacy. Social networking sites are public.
If you absolutely must use the net to transfer sensitive information use encrypted email. Never trust any social networking site, or regular email, to be private because it is most assuredly not private. Your communications can go through many servers to get to its destination and can likely be read at all of them.
