I use ES file manager.
Like I was saying in another post. Google failed to provide the most basic operating system functions like a file manager.
I have to add to this list:
Camera launcher
Ability to transfer files over the USB port to portable media. (flash drives, usb HD and SSDs, and maybe other phones and mp3 players)
Auto backlight that goes 'down' not just 'up.'
Home screen that goes into 'portrait' mode.
DLNA/UpNP client program.
Volume control that goes high enough for loud places.
These are all software issues.
Google should stick to what they know best - Maps/nav, search, e-mail and that's about it!
I'll have to say the voice recog. and speech is a big plus for the N7 usefulness.