Forget prediction games in a forum. If you want a pool there are some online, I am doing one at work and with some friends at
www.jocandi.com . It's straight-forwarded, allows you to predict each game upto 5 hours before kickoff, calculates rankings of pool participants, and costs $1 or 1 Euro to play (payment by paypal to purchase seats). Downside is you have one day to organize and get people signed up. If anyone is interested in my pool ($10, winner takes the pot), send me an U2U but we don't have too many spots left. thanks