The Project Akita OS (Orange OS) was started with the intent to design a lightweight operating system. It contains a small kernel designed for those interested in the low-level, practical aspects of building an x86 system. The host development environment is designed to work around the Bochs x86 emulator, so that you can easily test changes to the kernel.
NanoNAS is a Network Attached Storage (NAS) server operating system designed to transform a basic computer into a dedicated HTTP, SMB/CIFS, or AFP file server. It fits on a single floppy disk and is intended for use in any low-security environment or application that requires the simultaneous availability of large amounts of inexpensive networked storage.By design, it is a community workgroup server and does not support features such as user management, disk quotas, or the ability to join domains. However, it is very easy to set-up, to administer, and to use.
PXE Knife is a tool for booting various floppy based utilities via syslinux, allowing them to be booted off a CD, a hard drive, or over the network via PXE. PXE Knife can be used with a number of commonly used tools such as hard drive manufacturer's utilities, memory testers, Linux recovery disks, Windows password changers, pre-configured PXE Knoppix booters (just add DVD), and a number of other utilities. It takes advantage of syslinux's menu system, so it's easy to navigate.
alcolix is a minimal Linux rescue distribution with the goals of being small, compatible, and very usable. It has a cozy shell and a multitude of partition rescue/editing tools, all based on up-to-date releases (e.g., 2.4.x kernel with USB support). It uses cpio.bz2 data disks and has a full GRUB bootloader, memtest86, and more.