Randym Apps has Stop and Go (iTunes Link) in the iTunes App Store for FREE for a limited time.

Stop and Go is a new game for iPhone and iPod Touch whereby players control stoplights in order to get cars safely through the intersections and off the board. If you wait too long to change the lights, cars will start to back up. If the cars back up to the edge of the screen, new cars will push onto the level and cause crashes!

Cars range from slow, small blue hatchbacks and large yellow busses to fast red sports cars. Use the different cars to your advantage and create gaps in traffic to get a higher score.
You get one point for every car safely exiting the board, there is a checkpoint every 50 cars which can now be reset as well.

Additionally, cars can run out of gas, which can either allow a reprieve from the action or block your intersections!
The game has elements of strategy and action as players try to safely navigate cars off the board. The game features 3 levels, 2 additional downloadable levels packs, checkpoints, OpenFeint high score and trophy support, and cool retro graphics.

Don’t worry if all of this sounds confusing, there is an in-game tutorial to show you how to play, including clicking on a light to change it from red to green, and how to touch and drag the gas can to refill a stopped car.