I have a Zune and download DRM-ed music via the Zune Marketplace that I can listen to as long as I have a Zune Pass monthly subscription. Is there any way to listen to this music on my Droid?
There does not appear to be a way, no. (Some information in this forum thread: http://www.droidforums.net/forum/droid-audio-video/40610-zune-not-droid-friendly.html)
Apparently, DRM'd wma files require a Zune device. Since Droid ≠ Zune, it's not going to work. Unless and until Microsoft decides they want to build a Zune App (à la the way Amazon has a Kindle app) you're out of luck.
Only option appears to be to burn those tracks to a CD, then re-rip them as DRMless MP3s.