Launchpad Single Sign On
I like that the "Ubuntu One" cloud account goes hand in hand with the operating system, and now there's a music store... It seems like it has potential to be the online account to be associated with an Ubuntu user, in his capacity as an Ubuntu user. I think that potential could be well approached if there was a way to use your Ubuntu One account on these forums. I'm not sure how exactly they would be integrated... I just think that they can be, to some greater end.
Granted, I can always just use my Google account or Facebook account... Maybe Canonical can start pulling together a greater online social-media-style presence?