More recent versions of bootcamp will allow you to create a USB Windows installer from an ISO.
When you go through the bootcamp assistant, it will give you the option to create the USB drive. Just point it to your ISO and follow the rest of the instructions.
Also, in case anyone is wondering, there are legitimate download links for (at least) Windows 7 ISOs. These are direct from Microsoft.
http://answers.microsoft.com/en-us/windows/forum/windows_7-windows_install/how-to-obtain-iso-to-reinstall-windows-7/59b6b659-7a04-4df2-9bae-ddac79c9389f