How to avoid entering Cloud credentials in many apps
You might want to take a look at Cloudii. I don't use the cloud myself, but if this app keeps it promises, it...


  is the best app to manage all your cloud services within a single app. Cloudii brings full service integration as well as a powerfull synchronization tool.


It even integrates multiple cloud services (currently: Google Drive, Dropbox, Skydrive and Box -- more to come). According to its description, it lets you both navigate your cloud-stored files and keeping them in sync (the screenshots support this idea).

Note, however, that the free app is a 14d trial only, which afterwards requires an in-app purchase. I don't know the price, but as one comment put it: I'll be glad to buy the developer "coffee"!