LinkedIn is awesome for this. You need to connect with lots of people though to really leverage your networking. Start with guys in your current squadron, friends, relatives and then start looking at the suggestions given by LinkedIn. It's amazing how quickly you'll start seeing old coworkers that are now airline pilots.

I know that I fully welcome hearing from old buds, and helping folks out is really the only reason I keep the account open, now that I have my airline job.

PS (4fans) don't limit yourself to just Delta, apply to all the majors and get a bird in hand if you can.