One thing I've noticed on the boards, and maybe you've noticed it too: we keep seeing the same folks reading and posting here. It's actually a pretty small crowd that hangs out here. Diehards. The Elite, if you will. HMX has been pitching RBN hard at you guys, and you've been knocking 'em out of the park, and I think that I can speak for most artists in saying that we're grateful.
But it's not enough, I fear.
If RBN is to really be successful for the artists here (and incidentally, for HMX) the word has to get out to the masses of more casual players and fans: people who have Rock Band, but maybe have it in their closet and haven't added new songs for a while, or people who haven't taken the plunge and bought the game yet. And I don't think the casual gamer has noticed RBN at all, frankly. I think they've noticed Lady Gaga and all that, but they really haven't been targeted with RBN as far as I can see. And truthfully, the casual listener will have been discouraged by sub-par preview audio, lack of information about new artists, and clumsy music store navigation. (These are things I trust will one day be fixed, but there have been opportunities lost here.)
There's only so much most of the artists can do. We can put out the word to our fans, and to be sure, we do: but the reality of the situation is that there is a far higher percentage of GAMERS who like music, than there is of MUSIC FANS who game. (Heck, there are a lot of music fans who not only don't game, but actually viscerally HATE Rock Band. This is one reason why what little press the RBN gets is on Gaming blogs: music blogs have been pretty silent, and there's snobbery behind that. Screw 'em, I say.)
My point is that since the RBN can't really count on heavy promotion, what we really are going to depend on is YOU. Get the word out about music you like that you're discovering here. There's a reason a lot of artists here are giving mp3s away for free: Don't just consume it, share it. Spread it. INFECT people. Hotlink to it in your blogs and on your Facebook and in your tweets.
This is not going to be what it could be until a lot more people get involved with it, and that's not going to happen without your active involvement.