FlashMagic
FlashMagic (Now: Diagmagic) is a small package of useful tools to recover lost files, back up and restore your drives, diagnose problems with your computer, reset your root/administrator passwords, wipe your hard drive, chainload other OSes and more on a bootable USB flash drive.
It consists of Parted Magic, KonBoot, DBAN, memtest and some other tools.
Download
Diagmagic is powered by the wonderful Parted Magic, and many other open source tools. If you need the source code, just grab them from originating tools' sites (I just put them together :D)