If you find an app that does that, you might post about it, in case other users might like it.
For music, I'm increasingly using Amazon's cloud player app, because it lets me use my music across platforms, including my iOS, Android and Windows devices.
I've always tried to avoid buying content that would tie me to any one hardware maker, because I want the flexibility to take my content with me, no matter what hardware I choose over the years. I also am trying to wean myself off iTunes as much as possible, so apps like Downcast, Audible, Amazon cloud player, etc., are more appealing to me than ever.
As much as I like my iDevices, I also increasingly like Android devices. I'm interested in what Microsoft might come out with, too. I'd like to see much more competition for our dollars, because it puts pressure on companies to serve users better. For instance, if tablet competition were stronger, Apple couldn't as easily get away with breaking features, because we'd have more alternatives.
Even Apple fans should root for more competition, because that's the only chance of their not being entirely at the mercy of Apple's whims.