There is another spin-off site of Amazon.com, called Soundunwound . They set up a Gravity Tree page for us there:
Not really what we'd call a social network site at all, but more like their version of All Music Guide . The difference is that it looks like anyone can contribute more directly to the content. For example, Alan has been able to go in and add quite a bit of data (bio, etc.) even though we didn't set up the page.
We would be curious to see any of your contributions, if you are so inclined...
It looks like the site is still in Beta (and they've already changed the look of the site twice!), so we'll have to watch and see how it develops.