REQUIRES ROOT! USE AT YOUR OWN RISK!
This app moves apps from and to the /system/app folder, making them a system app or a user app. System apps can get more priviledges, so some apps get more functionality when installed as a system app.
On the other hand, system apps can not be uninstalled. So this app can also be used to convert system apps to normal user apps by moving them from the /system/app directory to /data/app directory.
WARNING: Uninstalling important system apps might result in a unusable device! Use this function at your own risk and only if you know what you're doing! Make a NANDroid backup first! I won't give any kind of support if something goes wrong - don't install this app if you're not okay with that.
Paid apps can not be moved! Since Android JellyBean, paid apps are encrypted and therefore can not be moved!
Apps which are moved to SD card need to be moved back to internal memory before being able to move them to /system/app!
The app might not work on custom ROMs!
This app requires a rooted device with BusyBox installed. Don't install this app if you don't know what that means!
Make a backup before moving files! Not every app will work when moved to a different location!
This app uses the RootTools Project (http://code.google.com/p/roottools) library.
The app is open source: https://github.com/j4velin/SystemAppMover
added yet another warning dialog as people still post reviews saying the app "uninstalled" an app -.-