Simple Rescue CD is a small Linux rescue CD, suitable for booting systems that have become unbootable due to filesystem corruption or other problems. It lies somewhere between minimalist boot floppies and large full-featured rescue systems, and as such is suitable for when space is tight, such as on business card CDs.
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.