Last night I dreamed that my ol' game buddy Gopher invited my daughter and I to this sweet new LARP he was into. Note that I'm confident that Gopher has never LARP'ed in his life. Anyhoo, the deal with this LARP is that it's a dungeon exploration type affair set in a sprawling concrete and steel complex that has been seriously wired up. Tiny cameras in every room, magnetic locks on some of the doors and wi-fi throughout the joint.
In addition to the usual costumery and props, every participant carries a smartphone of some sort. Want to 'pick the lock' on one of the maglock doors? You play a little lockpicking minigame on your iPhone or Droid or whatever. Spell casting also worked through the smartphone. Select light off of your spell list and remote controlled lights come on wherever you are at. Cast clairvoyance and the phone shows you whatever the nearest hidden camera is picking up.
In the dream your phone also somehow tracked hit points. You couldn't die in the middle of a fight, but after defeating the badguys you might get a text message telling you that you're dead.