Cogs is a 3D puzzle game that was originally released on iOS over a year ago, but it has just arrived on the Mac App Store. It's a good one, featuring a completely "mechanical" interface and sliding tile puzzles that build various contraptions of varying difficulty. The app is US$4.99 on the Mac App Store, but it's even cheaper on iOS; it's completely free on the iPhone right now, and it's $2.99 on the iPad as Cogs HD.
Unfortunately, even at those prices, the Mac App Store version is probably your best bet, as it comes with all 50+ levels unlocked and ready for play, while the iOS versions require separate level pack in-app purchases to get access to everything. Still, the free version comes with 10 levels anyway, so if you just want to test out the gameplay, you can. Unfortunately, there's no Game Center integration at all (the app was originally released before that), but maybe now that the Mac version is live, we'll see an update in the future. Whatever happens, if you haven't played this one before, it's definitely worth a look today.