iPad: If you're the type to spread you files across multiple cloud storage services like Dropbox, Google Drive, SkyDrive, and others, then you likely have a bunch of apps loaded up on your iPad to access them. Documents by Readdle gives you access to all those in one place.
Documents by Readdle is a surprisingly robust app. Not only can you access all your cloud services, but you can also access files from computers on a local network, or FTP. From there, you can transfer files across services, copy them to your iCloud drive, or just load them up to view. You can also listen to MP3 files, watch videos, read and edit documents, and annotate PDF files directly from the app. If you're looking for an all-in-one file browser that has access to a variety of services, Documents by Readdle is worth a look.
Documents by Readdle (Free) | iTunes App Store via The Verge