What do you do when waiting for an appointment, or the train? When I am in this situation, I have been playing Luxor on my phone. This is a pretty addictive game. It is a game where you need to match three or more spheres of the same color, in a moving row of spheres, before the spheres get to the end of the track.
This is game works well a cell phone with the simple controls, and with a small screen. It looks like this game is also available for Mac OS X and Windows, and for online play.