The popular, open-source media player firmware Rockbox has recently been made available for Android. Rather than run as an operating system, Rockbox operates as a standalone application that you can install as usual with an APK. Development is still on-going, but Rockbox dev kugel has a few pre-compiled APKs hosted for you to try out if you’re interested.
These builds are unofficial and are purely for demonstrative purposes, but they seem to work pretty nicely. Currently the navigation/control interaction method is touchscreen only, and screen rotation is not supported - Rockbox will only run in Portrait orientation. The controls are rather confusing since they don’t actually appear on the screen. Specific zones are mapped to buttons. Below is my best estimate of what the screen control layout is, through trial and error.
If you’re running the WVGA version, first thing you’ll want to do is go down to Settings > Theme Settings > Font and choose Helvetica to make text a much more legible size. There doesn’t appear to be an option to limit your Database scanning directory, so all of the Android sound files show up in my library. Of course, the beauty of Rockbox is its configurability, so there is probably something like an XML file you can edit to limit your database.
Rockbox is definitely an application for the “enthusiast,” so don’t be surprised if you find it a confusing interface to work with. Still, I love Rockbox on my Sansa Fuze, so it feels like Android just got a little bit more homely. Check out the Reddit thread below for more tips and details, or head on over to the Rockbox Wiki for information about the Android project.