Another Humble Bundle:
Humble WB Games Bundle
Again, Steam keys and just one game native for Mac, but it's a good one: Batman: Arkham City Game of the Year Edition.
$29.99 in the Mac App Store, but you can get it for 5 bucks in the bundle.
Also included if you're a PC gamer:
- Batman: Arkham Asylum GOTY
- F.E.A.R. 2: Project Origin
- F.E.A.R. 3
- Lord of the Rings: War in the North
- Scribblenauts Unlimited