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.
Tiny Core Linux is a 12 MB graphical Linux desktop. It is based on a recent Linux kernel, BusyBox, Tiny X, Fltk, and Flwm. The core runs entirely in memory and boots very quickly. The user has complete control over which applications and/or additional hardware to have supported, be it for a desktop, a nettop, an appliance or server; selectable from the project’s online repository.