MTV really understands how to utilize rich media on the web. During the broadcast of the VMAs on tv, they also have a live broadcast from backstage on vma.mtv.com. It totally rocks! And it's syced perfectly. I'm a fan of their Overdrive site, but this brings it up another notch. In addition to the live stream, you can also instantly see performances on demand right after they broadcast.
If only more media companies would truly understand how to use the web.