waitfordevice is a tool that waits for a device to become available. One can use this, for example, when waiting for a USB device to be fully ready after modprobing the USB subsystem (which runs async). This tool can be used in startup scripts or other scripts that need to use a device. It is better guaranteed to work (and more efficient) than using a couple of sleep statements.
Finnix is a small, self-contained, bootable Linux CD distribution ("LiveCD") for system administrators, based on Debian testing. You can use it to mount and manipulate hard drives and partitions, monitor networks, rebuild boot records, install other operating systems, and much more.
Super Grub Disk is a bootable floppy or CDROM that is oriented towards system rescue, specifically for repairing the booting process. Super Grub Disk is simply a Grub Disk with a lot of useful menus. It can activate partitions, boot partitions, boot MBRs, boot your former OS (Linux or another one) by loading menu.lst from your hard disk, automatically restore Grub on your MBR, swap hard disks in the BIOS, and boot from any available disk device. It has multi-language support, and allows you to change the keyboard layout of your shell.
Coreboot (formerly known as LinuxBIOS) is a project that aims to replace the normal BIOS with a little bit of hardware initialization and a payload. Payloads can include a compressed Linux kernel, FILO, GRUB2, OpenBIOS, Open Firmware, SmartFirmware, GNUFI (UEFI), Etherboot, ADLO (for booting Windows and OpenBSD), Plan 9, or memtest86.
HeavenOS is an original, alternative 32-bit operating system for Intel 80386 compatible processors. It is made with NASM (The Netwide Assembler), and is not intended to compare to modern operating systems, but to try to get the best features and discover better ways to do things. It is intended to be a simple and pratical platform for development, running with a small amount of code.
mbldr (Master Boot LoaDeR) is a boot loader which fits into the first sector of an HDD (MBR). It allows the user to choose which partition to boot and is intended to replace an MBR that comes with DOS/Windows (fdisk /mbr). It may boot OSes above the 1024th cylinder, and Linux and BSD are also supported. mbldr is based on OS Boot Select (OS-BS) project by Thomas wolfRAM.