WinToUSB will install and run the Windows operating system on a USB hard drive or USB flash drive, using an ISO image or CD/DVD drive as the installation source.
Rufus is a small Open Source utility that helps quickly format and creates bootable USB flash drives, such as USB keys/pen drives, memory sticks, etc. Rufus is now integrated with Fido to download Windows 10 and 8.1 ISOs from Microsoft servers. Video guide available.
USBDeview is a small utility that lists all USB devices that are currently connected to your computer, as well as all USB devices that you previously used.