I saw him open for Limp Bizkit quite a few years ago (along with Papa Roach), and it was an awesome show. I was never at all interested in him until then, and admit that I do have all of his stuff on my iPod now... even if I don't listen to it all the time, it's a nice change of pace every now and then.
And the final "rap battle" scene in 8-mile was pretty awesome.
NSFW