www.silverplatter.info covers most of the venues downtown. The nice part about looking for a live show these days is that almost every band has a myspace page. You don’t have to wait for a band that you know and love. Whenever you feel like seeing a show look up who’s playing on silverplatter and then hear a sample of their music on myspace. I’m sure you’ll find something to get into. The Phoenix music scene is much better than one might expect.
I also found a nifty calendar called Phoenix Agenda – “The independent concert listing for Downtown Phoenix”. Unfortunately I could not find it online. This was volume #1 for April so it may be still be coming.