Riptide GP: Renegade, I think I paid $3. It's a straight up racing game set in some future racing hopped up futuristic wetbikes through a variety of challenging tracks. Tilt to steer and finger dancing to do tricks. May not be for everyone, but I have definitely enjoyed it more than 3 bucks worth.

Also Zen Pinball, yes it only comes free with one table, but it's not a terrible table and for a few bucks a piece the payed tables are works of fucking art, it plays well and has been around long enough to have some very slick tables available.

Neither of my suggestions are free, but I feel that they are both cheap at what you get for the price, and I don't mind paying devs that aren't trying to fleece me.