GRUB - Multiboot boot loader
EasyBCD - EasyBCD is NeoSmart Technologies multiple award-winning answer to tweaking Windows bootloader.
Grub2Win - Safely dual boot Windows and Linux without touching the Windows MBR.
Systemd-Boot - Systemd-Boot, formerly known as Gummiboot, is one of the simplest UEFI boot managers that lets you boot Linux and Windows in EFI mode even if the system is BIOS only supported.
rEFIt - rEFIt is a boot menu and maintenance toolkit for EFI-based machines like the Intel Macs.
U-Boot - Das U-Boot (the Universal Bootloader) and Embedded Linux