Mac OS X Tiger only: ATV4mac runs Apple TV take 2 as a Mac application, bringing all the cool multimedia features of the Apple TV to your Mac. ATV4mac is a fairly young project, hence the unfortunate Tiger-only support at the moment, but it's already sporting most of the features available to Apple TV along with a few of its own. ATV4mac is freeware, Mac OS X Tiger only. I wasn't able to try it because of the Tiger limitation, but if you give it a go, share your thoughts in the comments. If you're dying to get more advanced media centre support than Front Row has to offer but you've already upgraded to Leopard, check out previously mentioned XBMC for Mac.