One of my favorite ways to waste time, is to play SuperTuxKart. It has no support for game-pads )yet), so I set the controls with a utility called Gamepad Companion, the keyboard controls are configurable; and since the controls are digital, it is fun to play with the keyboard. The game is available for Mac, Windows, Linux & and the source-code is available. The developers are implementing a new physics engine, but currently you stop if you are hit. If you drive into a banana, you might get a bomb that will go off unless you rear-end another player.
I have an SVN version with the new physics engine, you can flip over the kart, you don't stop if you hit another player, and in one track you can move around traffic cones. Their are still many problems with the new physics engine.
The menus are laid out nicely and you can navigate them with the mouse or keyboard.. You can select "Gran Prix,""Quick Race," or "time trial. There is also multiplayer for up to four players,
I play the game with a game-pad, although the game currently has poor game-pad support. I use an extension called gamepad companion to map each button to the correct keys, I have 3 gamepads configured this way. A: MacAlly iShock 2, a Logitech cordless rumblepad 2, & a MS Sideinder.
This game is fun, addictive, non-violent and free. It has a lot of potential, on rare occasions it may crash and require a restart. But don't let that stop you.