Alright, you asked and I've done it! As @pfunk pointed out in my last post, the stored keys were stored in plain text. This has now been fixed and keys are stored with AES encryption. If you guys would please look through the code and/or try the app and let me know where it could be improved. The code is well commented and easy to understand.
In the mean time we will be working on the custom API for this project. Let me know what you think in the comments below!
The source code is here:
https://github.com/kodaxx/steempay
The release APK for Android is here:
https://github.com/kodaxx/steempay/blob/master/dist/steempay-alpha-encrypted-debug.apk
In the README there are simple instructions to build this from source yourself in less than 5 minutes using Phonegap Build, as well as a video describing the process here: