NOTE: This function should work on any device for which a custom ROM with Android 4.1.1 has been installed. However, some older devices may not have the hardware to support it or the ROM developer may not have included the necessary firmware. It should not hurt to try it though.
OTG (On The Go) is the term describing how some devices (including the Nexus 7) can support the USB Host function via the micro USB connector. The Nexus 7 has this capability but that capability has not yet been fully allowed. Here is a video that demonstrates using a USB mouse and a USB keyboard connected to the Nexus via a cheap USB hub.
This cable and the connection demonstrated should work on similar devices.
The Roo case for the N7 is available on Amazon for $9.98 + $4.98 shipping.
The OTG cable is available on Amazon for $0.68 + Free Shipping. The problem is that it ships from China and takes several weeks to arrive.
To get a mass storage device (USB Thumbdrive, etc) to work you have to install the StickMount app (from the PlayStore). The app sends a popup when you connect a USB storage device. You can read its contents at this location: SDCARD/usb storage/sda1
Use the notifications “pull down” to unmount the drive before disconnecting it!
Media that I know works: MP3 audio files work with GooglePlay; Photos display in the Gallery; M4V Video plays in the Gallery; DV, MPEG, MTS, and other video formats play with the BS Player or the VPlayer.
Leave a comment to tell us about other devices that you have (or have NOT) gotten to work with the OTG connection. We want to hear your story.