Just came across CloudRail library for Android and am adding it to MoneyManagerEx for Android. The library provides a unified API to several cloud storage (and other) services.
After Dropbox announced deprecation of v1 of their APIs and libraries, these needed to be replaced in the app. Now, for the same amount of effort in migration the app will get, for free, the ability to use four of the most common cloud storage providers. This is fantastic! Hope this stays a secret. :)