I'm not much of a gamer but I adore Crush the Castle. It's a medieval themed game where you use a trebuchet to knock down your enemies who inhabit an increasingly difficult arrangement of fortifications. It's a good test of skill and your knowledge of the physics of heavy airborne objects.
Today only, the full featured game is free, and in Uncle Mel's view it is definitely worth grabbing. It's great for passing the time in an airport, and can help you conquer your daily build-up of frustrations. The sound effects are super, from the screams of your victims to the subtle environmental sounds that match the locale in which a particular round takes place.
My only regret is that there is not yet an iPad version, but it doesn't scale up too badly and is still fun to play. If you haven't played this game, I recommend trying it. If you have only been using the 'lite' version, here's a chance to upgrade at no cost.
Thanks to Bill for the tip!