Some of my LJ friends have joined MySpace, and I also joined, but did not find it all that useful.
I've just discovered Tribe, which seems to be similar, but much simpler to use and more versatile in many ways.
I was looking for people who might be related, and one of my family names is Growden, and found that there is a singer Mark Growden who belonged to Tribe, and to contact him I'd have to join, so I did, and then started exploring what it could do, which is more than MySpace -- you can incorporate other blogs, like LJ, into it.
If anyone is interested, you can find me there at:
http://people.tribe.net/hayesstw