Zen Master Seung Sahn's Temple Rules
http://www.kwanumzen.com/misc/temple-rules.html

What The Buddha Said
http://www.geocities.com/Athens/Thebes/5683/BuddhaSaid.html

Teachings of Bodhidharma
http://www.cs.virginia.edu/~alb/zen/bodhidharma.html

Zen Texts
A large miscellaneous collection of Zen Texts.
http://www.sacred-texts.com/bud/zen/

BuddhaNet File library
Dozens of .zip files of Zen teachings
http://www.buddhanet.net/ftp11.htm

What do you think, my friend?
Selection of writings on Buddhism
http://www.serve.com/cmtan/buddhism/

Awakening 101
A free online Dharma course that explores the Enlightenment experience in the Zen tradition, presented by the Wanderling, an anonymous, uncertified Zen teacher.
http://www.geocities.com/the_wanderling/awakening101.html

Fukan zazengi
Translated by the Stanford Zen Translation Project.
http://www.stanford.edu/group/scbs/sztp3/translations/gongyo_seiten/translations/part_3/fukan_zazengi.html

How to Practice
The essential idea of Zen practice.
http://www.io.com/~snewton/zen/practice.html

Soto Zen Ancestors in China
The recorded teachings of Tang-dynasty Chan masters Shitou Xiqian, Qingyuan Xingsi, Yaoshan Weiyen, and Yunyan Tansheng, translated into English.
http://home.att.net/~sotozen

The Ten Precepts
Dai Bosatsu version.
http://www.digitalzendo.com/?library&step=7

Master Hsu Yun's Teachings
Dharma discourses by a historical Chinese Ch'an master.
http://hsuyun.budismo.net/en/dharma/index.html