Muppet Lab's Intercal Resources:Features the original specification and an extensive sample source code collection. Links to several compilers and to other Intercal-related sites.
C-Intercal Compiler: William Patterson's DOS port of the classic Intercal-to-C compiler coauthored by Eric S. Raymond.
C-Intercal Supplemental Reference Manual: Specification clarifications, implementation notes regarding the C-Intercal compiler, and literature references for those interested in background information on COME FROM and friends.
Catalog of Compilers Intercal Page: Idiom's catalog of free compilers and interpreters mentions Intercal.
Darren's First Intercal Program: This was author's first exercise in INTERCAL programming. It counts down from 500 all the way down to one. It's that simple!
Free Online Dictionary of Computing - Intercal: Short introduction to Intercal, detailing Intercal's distinctivenesses in comparison to other languages.
INTERCAL: Urban Nilsson's collection of INTERCAL programs.
Intercal "Hello, World" Program: Surprisingly readable chunk of C-Intercal-only source code written by Clemens Meier.
Intercal Programming Language Reference Manual: Original specification.
Intercal Resource Page: Unofficial Intercal language homepage, maintained by C-Intercal implementor Eric S. Raymond. Documentation, implementations, papers, and tools.
iperl: Using Intercal in Perl.
Jacob Mandelson's Intercal Page: Featuring a ROT-13 routine and a short link list.
Revised Reference Manual: Compiled from the original specification and from the comments and clarifications by Howell and Raymond.
The Language from Hell: Article and site, non-fiction, and journalism indexes.
The Pit: Intercal source code by Louis Howell.
Threaded Intercal: Malcolm Ryan's proposed standard for Threaded Intercal, version 0.2.