This app is one that I spend alot of time in and using daily. I access all my files, move, delete, copy, extract, backup, you name it. I know there is a few like this out there but Rom Toolbox is the best for me. There is a free version for you to try, but the Pro version is well worth the money. Below is a link to get the Pro version or search the play store for the free version to try.
Get Rom Toolbox Pro HERE
I access all my roms, kernals, gapps packages, and any other file that I can flash using recovery, which by the way I am currently running TWRP 184.108.40.206. I also access apk files to load on the device, backup/restore roms or apps, delete apps that I don't use from the system apps, and more.
Check out the screen shots I took from my device.
Screenshot_2013-09-04-17-15-24.png Screenshot_2013-09-04-17-15-33.png Screenshot_2013-09-04-17-15-42.png Screenshot_2013-09-04-17-15-48.png Screenshot_2013-09-04-17-16-13.png
Screenshot_2013-09-04-17-16-36.png Screenshot_2013-09-04-17-16-43.png Screenshot_2013-09-04-17-17-06.png Screenshot_2013-09-04-17-17-15.png Screenshot_2013-09-04-17-17-25.png
So these should give you an idea of what you can access and the app is very easy to go through and use. If you have any questions or issues don't hesitate to give me a shout.