Marc Hedlund has written a FAQ on CGI programming (URL is <URL:http://www.best.com/~hedlund/cgi-faq/> ) which makes a good introduction to the subject. The standard itself can be found at NCSA (URL is <URL:http://hoohoo.ncsa.uiuc.edu/> ).
For tips on overcoming common CGI problems, consult the CGI problems section and the section on granting CGI access to users.
Perl CGI programmers will be interested in the CGI Perl modules <URL:http://www-genome.wi.mit.edu/WWW/tools/scripting/CGIperl/>, which provide an elegant Perl 5 interface to CGI programming.
C-language CGI programmers will want to consider the author's cgic library. <URL:http://www.boutell.com/cgic/> Another C-language library for CGI programming is cgihtml <URL:http://hcs.harvard.edu/~eekim/web/cgihtml/> from Eugene Kim. A third library is libcgi from EIT. <URL:http://wsk.eit.com/wsk/dist/doc/libcgi/libcgi.html>
Borland Delphi enthusiasts should check out the Delphi class library for WIN-CGI programming offered by HREF Tools Corporation. <URL:http://www.href.com/>
Turbo Pascal for Windows users will be interested in a Turbo Pascal WINCGI interface written by Markus Schlarmann. <URL:http://141.2.61.48/tpwcgi/tpwcgi.htm>
C-language CGI programmers of the Macintosh system should check out Grant's C-language CGI framework for the Mac. <URL:http://arpp.carleton.ca/grant/mac/grantscgi/>