A recent post on BoingBoing pointed out this list
http://63.236.111.137/jsp/unpaidArtistList.jsp

Apparently, Sound Exchange used to be affiliated with RIAA, but is now
independent. They are charged with paying out the royalties for
streaming media, but if they can't find an artist after "due diligence,"
they get to keep the money.  This list is apparently a list of the
artists that they couldn't find.  The list clearly shows that they
aren't trying very hard.

But knowing that there are a lot of working musicians and people with
connections to labels on this list, I thought it was worth sharing.  If
anyone follows up on this, I (and BoingBoing I'm sure) would love to
know about what happens when one of these "missing" artists actually
asks for their royalties.

The original BoingBoing post is here:
http://www.boingboing.net/2006/09/21/exriaa_agency_cant_f.html