Man, how could I have forgotten about Tool and Lateralus? I love that album and it's my absolute favorite so far. Like I also mentioned in another blog before, System of a Down released Toxicity, which I think it's also pretty damn awesome.
Although the PS2 was released in 2000, I think this was definitely the kickstart of the 6th gen. My standouts from what I played so far are Halo and Smash Bros Melee.
Of course, all of this was done much later since I was only about 3 and 4 at that time and still only watched Nick and Cartoon Network on tv.