Facebook is fast becoming a hub for music discovery and marketing, That growth should accelerate when the social network announces its music plans on September 22nd. All of this makes engaging with fans on Facebook more important than ever, and a number of apps are helping to make that easier.  The four most popular apps to help musicians do that according to AppData are:

• BandPages By Root Music is the #6 Facebook App with 32M+ MAU (monthly average users).
• ReverbNation's Facebook app is gaining impressive traction reacing #25 with 12.5M MAU
• Bandsintown's live music app is at #117 with 3.4 million MAU
• SoundCloud charts at #281  with 1.4 million MAU