Critter Crunch. Amazon.com is currently selling game codes for half off the usual $7 price -- that's only $3.49!
It's likely that the PlayStation Store will also price-match this deal when it updates later today. But do you want to risk missing out on one heck of a deal? We think not.
Update: Burn Zombie Burn is also on sale for half off the usual $10 price. That's $5!