At a conference I helped organize last year called BarCamp, I ran a really fun session called HalfBakedDotCom.
It's kind of like entrepreneurial improv theater. You form teams and have 15 minutes to come up with a company, a product, a pitch, a marketing plan, revenue model, tagline, and logo. We have celebrity judges, and the best idea wins prizes.
amitgupta.com/blog/shoebox/2006/10/03/halfbakedcom-entrepreneurial-improv/
I took this video while teams were planning at a HalfBakedDotCome I ran this past weekend at MobileCampNYC, where we gave away six snazzy Nokia gadgets as prizes.