This list from CSS Tricks no longer accepts comments, so I'm extending it with my own take. But this is the official list of the web so I guess this is now the official list officially.

• Water.css

• MVP.css

• AttriCSS

• awsm.css

• Bahunya

• holiday.css

• Markdown CSS

• Marx

• Sakura

• style.css

• Stylize.css

• Tufte CSS

• Tacit

• Writ

• new.css

• bullframe.css

• magick.css