Facebook is a social strategy these days. Job hiring folk will look you up on Facebook, and your profile should look vaguely interesting, pretty normal, and absent of any incriminating pictures of you doing drugs, drinking heavily, stripping at parties, or whatever. Basically, if it's embarrassing or illegal, don't put it on the internet, but if you don't have any internet presence, it probably counts against you because everyone trusts people they know more about (barring 'omg I know you're a pedophile' or something) more than those they don't.