Here's my advice... get a rolodex, an organizer, MS outlook or a blackberry. Make a point of calling friends and coworkers at least once every 3 months or so and getting "reacquainted"!

I still talk to many of the people that I taught with and most of the people that I worked with at IDE. It's served me well over the years- if for no other reason than often having somebody to call and drink a few beers with on overnights! (My boss often asks/jokes "So who are we meeting tonight for dinner" when we're on the road...)