If you haven't already seen it on Equestria Daily, CrayolaBrony made a wonderful songbook for all the music in the show. It includes lyrics and the key signatures for each song. Bring it along for your next brony meetup so that you can all sing along together! Click here to see the songbook. Make sure also to check out CrayolaBrony's Deviant Art page.
CrayolaBrony is also working in collaboration with Everypony Sings to make a version with guitar chords. Stayed tuned!