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