BusyBox combines tiny versions of many common UNIX utilities into a single small executable. It provides minimalist replacements for most of the utilities you usually find in GNU fileutils, shellutils, etc. The utilities in BusyBox generally have fewer options than their full-featured GNU cousins; however, the options that are included provide the expected functionality and behave very much like their GNU counterparts. BusyBox provides a fairly complete POSIX environment for any small or embedded system.
Gujin is a PC boot loader that can analyze your partitions and filesystems. It finds the Linux kernel images available, as well as other bootable partitions (for *BSD, MS-DOS, Windows, etc.), files (*.kgz) and bootable disk images (*.bdi), and displays a graphical menu for selecting which system to boot. It boots the Linux kernel using the documented interface, like LILO and GRUB, so it doesn't need any other pre-installed bootloader. It can also directly load gzipped ELF32 or ELF64 files, with a simple interface to collect real-mode BIOS data. There is no need to execute anything after making a new kernel: just copy the kernel image file into the "/boot" directory, with a standard name. Gujin is written almost entirely in C with GCC, and it fully executes in real mode to be as compatible as possible.
minit is an attempt to cross-breed DJ Bernstein's daemontools and init, while adding dependencies, and maintaining minimal code base. It is possible to start and stop services on the fly. minit does not depend on a mounted /proc file system, and it does not write to any part of the file system, not even to start and stop services. It does not use System V IPC, either.
glogin is a program that can be used to cause a terminal (usually a virtual console) to be logged in automatically, without having to type a userid and password. Stick it in place of getty in /etc/inittab to have terminals come up logged in and at a shell prompt at every boot. Same purpose as 'alogin', but you use it a little differently, and it does a little more of the usual login stuff. It is a simple Perl program, and can be easily customized.