Win32 Disk Imager is an open-source tool for writing IMG images to removable devices, or backing up removable devices to the same format.

The program works with USB keys, SD and CF cards. It's not compatible with CDs or DVDs, and probably doesn't work with USB floppies, although the developer is unclear (the readme file says they won't work, the website says only that issues have been reported when writing to them).

The minimalist interface keeps operations simple. Enter an image file name, choose a device, click Read or Write, and wait.

There's one small extra in an "MD5 Hash" checkbox. Check this and the program calculates a hash value for your image file.