Rufus Portable

Rufus is a small utility that helps format and create bootable USB flash drives, such as USB keys/pendrives, memory sticks, etc. It can be be especially useful for cases where: you need to create USB installation media from bootable ISOs (Windows, Linux, etc.); you need to work on a system that doesn't have an OS installed; you need to flash a BIOS or other firmware from DOS; you want to run a low-level utility. Rufus is significantly faster than similar utilities and it's open source and free.