A Handbook of Statistical Analyses Using S-Plus
   By Brian S. Everitt; CRC Press, 2001, ISBN 1584882808. For applied statisticians, researchers, students. Introduces possibilities of S-Plus, S-Plus 2000, S-Plus 6, for data analysis.
   http://www.crcpress.com/shopping_cart/products/product_detail.asp?sku=C2808

ESS: Emacs Speaks Statistics
   Package for GNU Emacs, provides command-line, editing and transcript support for S-Plus on Unix, Windows.
   http://www.stat.math.ethz.ch/ESS/

S-Plus Help
   System for functions and datasets. Provided by University of Muenster, Germany.
   http://www.uni-muenster.de/ZIV/Mitarbeiter/BennoSueselbeck/s-html/shelp.html

StatLib
   Software and extensions for the S (S-Plus) language.
   http://lib.stat.cmu.edu/S/