So I've been asked to help a friend run a slide show for her wedding, and the hall is shaped such that we need two projectors so everyone can see. I need to show the same presentation on both projectors, obviously. The computers will be running a photo slide show during the dinner, and then there will be some game-type activities where the operator will control some slides. Option 1: Two computers, two projectors, load the same Keynote presentation on both, two operators both clicking "Next" at the same time. A lot of coordination, I need another person to help, and not very well synced. But this is my fall back plan. Option 2: Long VGA cable and splitter, so both projectors run from the same MacBook. Fair enough, but I need to buy or rent the long cable (looks to be about 100 feet!) and the splitter. Option 3: Two computers, networked over wireless, one screen-shares with the other so both see the same presentation. Haven't given this a try yet, was worried about frame rates for slide transitions. Anyone have experience with this? Option 4: Does there exist any software that I can run on one or both Macs, networked over wireless, that lets me load the same presentation on both, and them sync so that when I change slides on one, it changes on both? This doesn't seem like it would be all that hard, and it MUST exist (every Apple Store uses this sort of thing in their front displays) but I haven't found anything so far... I'm not worried about exact timing, but it should be close (e.g. the "slave" screen should change within a second of the first). Any thoughts?