Is there an app to control Bluetooth so I don't have to go into settings to turn it on and off?

Sorry but no there is no app that can do that. Apps are not alowed to change the setting on the device.

Hope it helps!

I don't think they want apps to change settings like wifi or bluetooth.

But it doesn't hurt to ask:

http://www.apple.com/feedback/iphone.html

Maybe they should put that option on the drop down screen that way you can stay on a music app. Heck you can post to FB and Twitter. Why not bluetooth and WiFi.