A whole slew of apps are going on sale this weekend, including Firemint's Real Racing 2 (which has dropped down to half price at US$4.99) and Grand Theft Auto: Chinatown Wars (also $4.99, down by the same discount). Adult Swim's hilarious little Robot Unicorn Attack running game is only 99 cents, on sale for both iPad and iPhone. In fact, all of the Adult Swim titles are on sale for just 99 cents, so you can look through those to see what you like.
I'm not sure what the impetus is behind this sale, but it's best not to ask questions. If you need a few new games to play this weekend (and honestly, I'm not sure you do, given all of the great titles on the App Store lately -- I'm still loving Battleheart), there you go.