A USB can do much more than just back-up your or transfer your files. It is much more capable than that. Your USB can perform many different tricks that might surprise you. Some of these are:
1.Lock and unlock your computer, secret agent style
2.Revive a virus-ridden system
3.Run portable apps, games, and utilities
There are 7 more things you can do but check the article to see them. I found this article interesting because it seemed kind of cool and weird. Some of the tricks are helpful too.
Vaknin, S. (2012, May 3). 10 awesome ways to use a usb flash drive. Retrieved from http://howto.cnet.com/8301-11310_39-57426513-285/10-awesome-ways-to-use-a-usb-flash-drive/