This is a message to everyone who is not registered in the LinkedIn social network of professionals. It will at least help you stay in touch with your former and current colleagues, classmates and friends and be informed of their career. It might also help you to find a good job or hire trusted professionals (or help the job/professionals find you). You may write recommendations to your colleagues and get recommended in return.

The major thing that impressed me is that I was able to find 3 ex-classmates already registered there as well as a good deal of my current friends who were keeping silence about it (bastards). Try it too to find out that everyone is already using it… except yourself
Leonid has already provided a sophisticated overview of what LinkedIn offers in his posting Get LinkedIn. Now. Seriously — please read if you are not convinced yet.