Pretty much just post what band local to your area you'd like to see on Rockband DLC. The catch, they have to be unsigned (and/or generally unknown).
Provide a link to some of their music so others can listen and give feedback.
Song: Torn in Two
This is a Sacramento, CA band that is currently in the running to open up for larger named bands in the upcoming Aftershock Music Festival. If you like them, please rate their video in the link a 5 so they can get in.