When Harmonix released Rock Band last year, I was dying to get it.  It was the next step that the Guitar Hero franchise which pretty much dominated the rhythm game segment of the gaming industry when it came out.  I had introduced my friends to Guitar Hero two Christmases ago, and despite all of the great games that had been coming out, GH was always the one we would come back to.  It's fun, it's challenging, but more importantly, it's one of the most team involving activities one could ask for.  Once you hit those notes in unison with your best buddy, to a virtual audience of thousands, there can be few experiences that are as satisfying.