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.
Ultimate Boot CD allows you to run floppy-based diagnostic tools from CDROM drives and consolidate as many diagnostic tools as possible into one bootable CD. An experimental feature also allows you to run UBCD from your USB memory stick on newer machines that supports booting from USB devices.