rEFInd is a fork of the rEFIt boot manager. Like rEFIt, rEFInd can auto-detect your installed EFI boot loaders, and it presents a pretty GUI menu of boot options.
rEFIt is a boot menu and maintenance toolkit for EFI-based machines like the Intel Macs. For newer machines, rEFInd, which is a fork of this app, and is still being developed, will be more suited.
AUMBI (Absolute USB MultiBoot Installer) is a free, portable app that allows you to have multiple Linux operating systems on a single USB (flash, thumb) drive.
DOS 5.0 - 6.22 Floppy Boot Disk Image is the original DOS 5.0, 6.0, 6.21, and 6.22 boot disks with IDE CDrom drivers included and even 5.25 disk image for DOS 6.22.
Floppy Boot Disk Images for DOS - Windows 98 contains all the floppy disk boot images you need to get any old operating system installed including DOS, Windows 95, 98, XP, ME, and 2000.