One of the common tasks in mobile development is sharing some application files between user's devices or storing files outside device. There are many cloud services such as Microsoft SkyDrive, DropBox, Google Disk, etc. allow developers to use their API's for these purposes. You may consider using a wide range of cloud services in your application and give users an opportunity to choose one to store and sync application files. This approach has some benefits and some disadvantages on the other hand.