Lightweight Distros

Damn Small Linux
Comprehensive information on dsl, wiki, forums, howtos, documentation.
http://damnsmalllinux.org/

Delilinux
Delilinux
http://www.delilinux.org/

Puppylinux
Puppylinux
http://www.puppylinux.org/

Tinymelinux
Tinymelinux
http://www.tinymelinux.com/

Xubuntu
Xubuntu
http://www.xubuntu.org/