Hi
You can use
QuickBlox, which is a cloud hosted platform to simplify your mobile app backend development. Try the Content Sample, you can use upload files, and create your own data-types. QuickBlox uses Amazon EC2 Platform.
Check
http://quickblox.com/developers/SimpleSample-content-android
They also provide Chat, Messages, Notifications, Ratings modules, and support for other Mobile OS and Web, if you want to build a Cross-Platform Solution.
Happy 2013!