coreboot!

The PLoP Boot Manager is a small program to boot different operating systems. You can boot the operating systems from harddisk, floppy, CD/DVD or from USB. You can start the boot manager from floppy, CD, network and there are many more ways to start the boot manager. You can install the boot manager on your harddisk. There is no extra partition required for the boot manager.

Like coreboot, libreboot is boot firmware intended as a free 'BIOS' replacement for your computer.

SeaBIOS is an open source implementation of a 16bit X86 BIOS. SeaBIOS can run in an emulator or it can run natively on X86 hardware with the use of coreboot.

Chameleon is a boot loader for Mac OS X.

gummiboot is a simple UEFI boot manager which executes configured EFI images. The default entry is selected by a configured pattern (glob) or an on-screen menu.

The "Universal Bootloader" ("Das U-Boot") is a monitor program.Free Software: full source code under GPLhosted on SourceForge: http://sourceforge.net/projects/u-boot production quality: used as default boot loader by several board vendorsportable and easy to port and to debugmany supported architectures: PPC, ARM, MIPS, x86, m68k, NIOS, Microblazemore than 216 boards supported by public source treemany, many features

XTIDE Universal BIOS makes it possible to use modern large ATA hard disks or Compact Flash cards on old PC's. You can then enjoy quiet or noiseless drives with more capacity than you'll ever need for old computers.