Allmusic has been moderately popular over the past decade, but it's my opinion they could get the site and service to explode by opening it up a bit more. Turning it into a myspace would be a complete disaster of course. But public submission with a bit more control would let them expand and fill in holes much more quickly as well as help build that powerful sense of community that drives the world's top sites (and the sole reason for these sites' top-dollar valuations).

I thought that the CDDB didn't accept submissions from the general public either (since having gone strictly commercial a few years ago).