If you have a Nexus 7 you'll know that the storage space is limited due to the small memory sizes available.
Now there is an app which enables Nexus 7 users to get USB drive support and expand their memory.
Nexus Media Importeris an app which allows you to import and stream music, videos and pictures from USB drives or an SD card. No root needed at all.
You then just need to buy a USB cable which will enable you to connect other USB devices to your Nexus 7. You can get them really cheap on Amazon.
Then you're ready to go. Now you'll be able to import pictures from your camera or watch movies straight from your hard drive.
Of course then can also work with a lot of other devices too, not just the Nexus 7.