Yes, you can buy the kinect alone, it runs about $110 this year. Last year it was $150. I bought my wife the kinect as her "big gift" for xmas last year. It does come with a game, basically to show off all the crap the device can do.
Downloaded a bunch of demos. Just Dance is ridiculously hard for my fat white no rhythm having ass. The Biggest Loser is supposed to be the best fitness game, so I tried it. I think I was bleeding from my sweat glands in the first few minutes. Holy shit, do I need to stop eating garbage. I'd like to try the UFC Fitness one, but I think it might kill me.
Alright, I got Kinect as well for a Christmas present. I told the person that bought it for me that I haven't touched my xbox in months and really didn't want to game that much anymore... So... they got me a kinect. Lovely. Anyway, I almost just gave it back to him and told him to go get his money back. I appreciate the thought... but I was telling him that so he wouldn't get me anything that involved video games. Anyway... Not sure what to get, because all of the games look like shit to me.
Grabbed both Kinect Sports today. Been playing for several hours with my friends. Tons of fun. Highlights - bowling and darts. Both are fun as hell, and you don't have to ever actually leave your home.