Second Life kind of oozes out into the web.
It finally rose to conscious level when I read about Lively, and how people are upset that others have signed on and beat them to establishing a Lively avatar with their SL avatar's name, but it's been going on since well before my rez day... on which I immediately set up email@example.com as my email address.
SL snapshots populate flickr, despite the controversy over whether they're "screenshots" or not.
There are so many social web sites for SL avatars that I can't keep up with them; my homes on them have virtual cobwebs. (Many have a blog option, but I barely come up with enough to keep this blog--another leak from SL into the general web--from gathering dust.)
It makes sense; after all, LL has enough to do without setting up purely in-world email, much less something like playlist.com. For that matter, it spreads the word about SL. With any luck, people will happen across SL blogs and get the idea that no, it's not all about [pause to try to come up with all the media cliches, a la "You Never Even Called Me By My Name"] pedophiles griefing furry Nazis and Goreans from their mom's basements.
Sorry... I don't have any grand conclusion or thesis. It just occurred to me this morning. I wonder what future historians will make of it.
P.S. I guess this shows I'm an immersionist. An augmentationist would respond, "Well, duh!" (possibly more articulately); there's nothing unusual about people who just happen to use SL also having web pages and blogs and flickr/myspace/etc. pages.