For me, the two games that I'd just plain like to see are Halo and Myth III. Fortunately, not only are both coming to the Mac, they are also most likely going to come to MacOS X (well, Myth III is, at least, and they'd be stupid to only have a MacOS 9 version of Halo).
Actually, I'd also like to see a MacOS X version of either SimCity 2000 or SimCity 3000, but I know those probably won't happen. I've never even seen SimCity 3000, but if it's only half as cool as SimCity 2000, then it's übersweet.