Portable Linux is a tool that lets you create bootable USB and removable drives using popular Live CDs based on Casper (like the Ubuntu family of distributions). It sports some unique features. The live setups it creates let you use the remaining disk space on your USB drive to store and transport files between computers, as usual. If your distribution supports persistence, the files and settings you edit on your live Linux distribution are persisted across reboots. Finally, you can access the area used to store your files from within your Linux distribution.
SoL-diag is a diskless Linux distribution that was designed for the rescue and analysis of i686 computers. The 36MB image contains over 300 programs, including DVD and MP3 players and CD-RW buring tools. It is also useful for improving your Linux skills and benchmarking computers without having to install programs to the hard drive.
Frugalware is a general-purpose Linux distribution designed for intermediate users who are not afraid of text mode. "The Frugalware Philosophy" is about simplicity, multimedia, and design. The authors try to make Frugalware as simple as possible while not forgetting to keep it comfortable. Frugalware uses Judd Vinet's pacman package manager.
Ubuntu Christian Edition is an operating system geared towards Christians. It is based on the popular Ubuntu Linux and includes the best available Christian software, such as GnomeSword, a top of the line Bible study program, and several additional modules. It also includes fully integrated Web content parental controls powered by Dansguardian and a graphical tool for adjusting the parental control filter settings. If you are looking for a KDE-based distribution, consider Ichthux.
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.