In all seriousness, a cellphone and a friend who owns a serious 4x4. The worst I've ever gotten my Jeep stuck we had to jack up each corner one at a time and stack rocks under each tire, then build a path of rocks to drive on until we got up enough speed to clear the bad spot.

Since installing some serious MT tires and lockers in both axles I don't do "stuck" very often. A snatch strap (good one from Warn or someone, not a Harbor Freight tow strap) would go a long way, as well as making sure that you have adequate recovery points.