1) You are correct with the iPod running at USB 2.0, as it does not support USB 3.0.
2) I haven't really see any other device using USB 3.0 besides external drives. Currently, the most practical use is as an external storage / network drive were information is quickly transferred or backed up on the drive. It can become a more useful tool for other devices, as they adapt the USB 3.0 standard.
i must admit that i have been looking for a case for my first build and while i have been impressed with some cases having more than one usb 3.0 on the front i/o port, apart from my iPhone i too have wondered what other devices get plugged in there. you've asked a good question as i feel you've beaten me to it. even if you are to plug an external hard drive in there, i'd that be plugged in at the rear as i for one don't like to see trailing wires sticking out in front of me. the iPod / iPhone wire is only temporary measure as probably aleady know.