Mac users interested in 9-ball pool generally download:
Pool Rebel+ is a very realistic, multi-platform Pool game. It is available for Mac, PC, Android, Ovi and iOS. This is relevant because the game has a multi-player mode, and you can play with friends who have the game, regardless of what platform they use. Pool Rebel+ lets you control every aspect of your game, and it has different difficulty modes that make the game challenging and fun to play.
Pool! lets you play a short game of 8-ball on your Mac. The game was originally released for the iPhone and iPad, and it has been available for the Mac for some time now. It is currently one of the most popular free applications on the Mac App Store. The game is rather basic.