Below you can find some (older) IT and Security-related remarks, tips & tricks:

In order to install the aforementioned (multiboot Linux USB drive creation utility), try this procedure (there are - of course - several ways to achieve the same result, but this one has worked for me):

1. open a Terminal window and enter: sudo apt-add-repository 'deb http://liveusb.info/multisystem/depot all main'
2. run sudo apt-get update
3. if you (as I did) get an error saying "The following signatures couldn't be verified because the public key is not available", leave the Terminal open and open a second Terminal window
4. in the second Terminal window enter: sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys [KEY] - where [KEY] is the key value listed in the error above (just c/p the alphanumeric part after NO_PUBKEY, e.g. 40875EAF436D04B4)
5. run sudo apt-get update again (this time around you shouldn't get the error message)
6. run sudo apt-get install multisystem in order to (finally) install the software (warning: it can take up to several hundred MBs of downloaded packages, as it basically installs QEMU and VirtualBox components)
7. run (and enjoy) the sofware (it should be available / listed as any other application) :)