Multi-boot, such a lovely word. Reminds me of Lilo Dallas Multi Pass from The Fifth Element. But essentially, multi-booting is nothing special. I have a system with four operating systems installed side by side just on the internal disk and another four or five on an external device. I have several systems with two or three instances of Linux distros breezing happily. But having a live bootable multi-boot system is a different story altogether.
Why would you want something like that? Essentially, a single all-purpose distro ought to do it. And now that you've learned about live CD/DVD/USB persistence, then all seems to be well. But sometimes you may require multiple distributions and/or non-Linux operating systems to do whatever you need to do. Usually, this kind of need revolves around system administration and maintenance, forensics, rescue, backups, and similar tasks. All right, let me show you how this can be done.
Teaser
YUMI We will begin with a Windows tool. YUMI is another useful Pendrivelinux.com tool, which lets you work with your distribution images and USB drives. In this particular case, YUMI stands for Your Universal Multiboot Installer. You can read more about its functionality on the website. Essentially, it works just like the regular USB Installer, except that you can place multiple items onto your drive. That was easy.
YUMI
MultiSystem This is a powerful Linux tool that can create bootable multi-boot systems for you. The range of features and options is quite impressive, but rather than droning, let me gradually expose them.
To setup MultiSystem, you will need to download (direct link) the installation script, which will then configure everything for you, including installing additional required packages from the official repository, plus it will add its own. The website itself is in French, so you may want to grab the script above and start working with it. Some basic knowledge of the command line