BigNoseBird.Com CGI Script Archive a superb selection of scripts, some we use ourselves
(In alphabetical order)
CGI City a one-stop-shop for people with CGI requirements (listed in 35 categories)
CGI Script.net a selection of excellent scripts including the csRecommend script
CGI Scripts by VerySimple some great free scripts (SimpleSubmit, SimpleSecure, eList, etc)
Dada Mail (was Mojo Mail) a CGI-based e-mail list management script
Fluid Dynamics: Freeware CGI Collection a good selection of free CGI scripts
Matts Script Archive probably the most famous script resource site on the Net!
The CGI Resource Index links to thousands of scripts in dozens of categories; sensational!
UniNetSolutions.com an excellent source of free (GNU license) scripts, with Helpdesk