I've experienced the "zone" when working on an intense math problem or programming. I used to get it from playing guitar too, but that has faded as I've picked up the guitar less and less.
Oh wait, I wrote a 6-page essay in less than two hours because my original one went to hell (damn them floppy disks). Luckily I had all my sources on hand annotated and all, so it wasn't too hard. I guess general stressful situations get me into the zone.
Also, a few days ago when a friend and I replaced the brake pads on my car. I'd never done anything that mechanically automotively involved without supervision before. It was raining and I was getting sick of the grinding noise my brakes were making, so in the spur of the moment I called up my friend and asked him if I could use his garage for this purpose. Since he's cool, he said sure. Plus it was cold out, so we fought the elements while getting our clothes and hands dirty. It was totally awesome. Got into a semi-"zone".
