Hyatt just announced their latest Faster Free Nights (FFN) promo for this year:
Every Two Stays = One Free Night
Plus earn 2,000 bonus points after every two eligible stays
With your MasterCard® card
September 1 - December 30, 2008
Redeem your award between September 15, 2008 and February 28, 2009
If you play it right, faster free nights can be an amazing deal. Two years ago I parlayed two ~100/night stays in a bay area Hyatt into a free ~500/night stay at the Grand Hyatt Tokyo. Just remember it is stays and not nights that count. You have to register for the promo before your first stay.