Damn Small Linux

Homepage: http://www.damnsmalllinux.org/
USSG Mirror: ftp://ftp.ussg.indiana.edu/linux/damnsmall/current/

Taken from Wikipedia
Damn Small Linux (also known as DSL) is a Linux distribution originally conceived as an operating system to run on lower specification systems, including computers which would otherwise come out of use. The distribution contrasts to most other Linux distributions by ranking hardware requirements of programs above other considerations.

As of December 31, 2006, DSL ranks as the eighth most popular distribution tracked on DistroWatch (which measures comparative popularity based on page views). This provides evidence of strong enthusiasm for operating systems capable of running on lower-end hardware.

Due to the small size of the complete distribution, it will run on smaller storage devices than most other operating systems, including bootable business card, 64 MB USB flash drive, CompactFlash card (through IDE connector) and ZIP drive.