This small $3 USB OTG (On The Go) cable opened up the world of USB peripherals to my phone. And I am excited!
I can hook up a keyboard (complete with a touchpoint and a touchpad) and type away. The touchpoint/touchpad worked. Even Alt-Tab to switch between running apps works flawlessly. I didn't have to install anything.
I can also hook up a USB thumb drive. And access files on it just like I do on my laptop, plus backup files on my phone to it.
With a USB SD card reader, I can backup photos from my camera to my phone! It is not often $3 buys so much potential.