The first is the games, Gears of War - Halo 3 - Mass Effect - Lost Planet - which you can view the trailers below. Secondly, Xbox Live and my buddies. I play with friends , buddies from work, all of whom are scattered either in different parts of greater Montreal, or elsewhere in Canada. Xbox Live gives me a chance to have fun with them, and sometimes poke fun at them.
Also, I get access to lots of content, especially with the Gold level. And third, the 360 gives me access to content on my PC which I can stream (once I get my wireless connection working!) through the console.