MultiBoot USB
This is a project that contains a collection of GRUB files and scripts that will allow you to create a pendrive capable of booting different ISO files.
Qubes OS is a security-oriented, Fedora-based desktop Linux distribution whose main concept is “security by isolation” by using domains implemented as lightweight Xen virtual machines. It attempts to combine two contradictory goals: how to make the isolation between domains as strong as possible, mainly due to clever architecture that minimises the amount of trusted code, and how to make this isolation as seamless and easy as possible.