I want to clone bootable USB drives (Windows 7 installation with image file). What's the fastest and easiest way to do this?
In Linux you can use just
dd if=/dev/sdb of=/dev/sdc
(assuming that sdb is source and sdc is destination usb memory)
In Windows you can check out for example this tutorial.
Late to the party, but ImageUSB is also a very good option. It clones the drive exactly, including the MBR. Note that you want both drives to have about the same amount of space, as if you write a 4GB image to an 8GB pendrive, you'll only be able to access the first 4GB until you reformat.
There is an windows version of dd available, too. If you have some knowledge of the commandline it is easy to use. dd for Windows
If you don't understand the manual i could try to explain it for you. It is free, fast small and simple. It could although be placed in an BartPE image.
I played around with dd and the windows equivalent, but the copy is a true image inasmuch as a 2GB stick will make a 2GB image/copy, regardless of the size of the actual partitions, and this can take a long time, especially with big sticks.
In the end, I used Clonezilla to make a partition backup to a local hard disk and these can be restored 'on demand' to new sticks with the added bonus that the partitions can be resized on the fly too.
This approach may be useful if you want to make a master image and then duplicate it several times but it's not a solution for as-and-when, pop in a stick and copy it.
Clonezilla is a convenient liveCD to use for those who do not normally run Linux or some other flavour of *nix. Booting off of a liveCD your USB devices will more than likely be realized and you will be able to essentially do the same thing as you would with 'dd' in a perhaps more friendly form.