Hmmm... unfortunately, I don't feel this thread is necisarry. There are Last.fm widgets in member profiles. If members have a Last.fm account, they're able to enter their username and have it displayed on their profile to share with others.
It seems like a good idea to just go to profiles and seeing if someone has a Last.fm account on it, rather than making a thread asking for people to share their account names so you can see if you have similar music interests. Seems kind of like posting a thread asking for friend codes, to me, which is generally not aloud, so I'm going to treat it the same way and just close this thread. ):
You can make a social group if you'd like!