In it's own sandbox, yes there are a few apps that allow for you to manage your apps. One that I would point out would be File Manager- Folder Plus, which will run you 5 USD in the AppStore. As for completely file management, that would require that you jailbreak your device to have full root access.
If your goal is to simply open up a few files that you've imported onto your device using say Wifi, DropBox and the like, then it can be done with File Manager. Here's the iTunes redirect page for it (You'll need iTunes installed on your computer or access it through your phone)