If you've ever run a Linux LiveCD (or LiveUSB), or booted from a rescue disk, you've probably used a version of SYSLINUX, even if you didn't know it at the time. SYSLINUX, the work of H. Peter Anvin, is a bootloader for Linux which can boot from an MS-DOS FAT filesystem or create a bootable floppy (very old-school!); its close cousin ISOLINUX handles booting from CDs and similar media. SYSLINUX has always been enormously useful for first-time installs, when you're often booting from a machine that is currently running Windows, but until fairly recently, you had to switch to another bootloader post-install, since SYSLINUX doesn't handle ext* filesystems.