YUMI (Your Universal Multiboot Installer), is the successor to MultibootISOs. It can be used to create a Multiboot USB Flash Drive containing multiple operating systems, antivirus utilities, disc cloning, diagnostic tools, and more. Contrary to MultiBootISO's which used grub to boot ISO files directly from USB, YUMI uses syslinux to boot extracted distributions stored on the USB device, and reverts to using grub to Boot Multiple ISO files from USB, if necessary.
It free and it publish it source code:
------------------ new version 2 --------------------------
Yumi V2
I am use it very often, and it really help me to create a USB with multiple OS (Ubuntu and Windows). and save my computer when it crash.
Tal.