The iMac may be a beautiful machine, but it is not perfect. You are going to have to reach at the back to connect your USB devices. That problem could be easily solved with a USB hub. The Jimi USB Extension is probably a more elegant solution. It brings a USB port to the front, so you can connect your flash drive or anything else you have. Just plug Jimi to a USB port at the back of your iMac, align its J straight down, and snap it into the air vent at the bottom of your computer.
Jimi is elegant and simple to use. You can plug it into a port of your choice on your iMac. Just bring your slim aluminum iMac (2012 or later), and you are set. You can get one of these for $14.95.