1. Live in a core market. Atlanta is one. So's NYC. There are others.
2. Go online! Check Entertainment Weekly and Chud.com regularly. We've also gotten free passes from Premiere and, believe it or not, Teen People - that's who was giving away the Harry Potter passes.
3. Go offline! Check your local indie paper - they'll sometimes have screenings. Check record stores - sometimes they'll get a bunch of 'em. I just do online, though. I'm lazy.
And there you have it.
Once you have your passes, keep this in mind: They send out a metric assload of passes. Like over twice the capacity of the theater. It's first-come first-served. Get there early.
Thank you, drive through.