If you had five minutes on stage what would you say? What if you only got 20 slides and they rotated automatically after 15 seconds? Would you pitch a project? Launch a web site? Teach a hack? We’ll find out during Ignite SF at Web 2.0 Expo SF. Happening Tuesday evening, this event will be similar to last year, but this time the Ignite audience will vote to select Ignite talks for the Main Stage.