Media Centers on the Mac have been pretty hit or miss so far. We've been playing with a few of them, along with Front Row and nothing has been really "sticky". One we're a huge fan of is open source Plex. It has been improving incrementally for the past year since it branched off from XBMC and basically does everything Apple's Front Row does, but better. You can use an Apple remote or there's built-in support for Harmony remotes. Plus it does a bunch of other interesting stuff like play 1080P movies in formats other than MP4 and MOV, streams weather information to your media center Mac, and it is skinnable.
But then something amazing happened.
Over the weekend we hit the 0.7.8 Beta version and ..erm.. Boom! They now have an App store! These apps bring together a lot of what you'd want in a media center. Obviously, you want to pick up Hulu, CNN, CBS