The Game of Set implemented in Haskell with a CGI interface.
There are a bunch of different implementations here that evolved into the CGI binary. I've left them here for posterity.
To use the CGI script, you must first create the card deck. As long as you've got ImageMagick installed, you can just make cards and it'll generate the deck; you can change the destination directory by editing the IMGDIR variable in the Makefile.
While you're in the Makefile, set the IMGURL variable to the base URL from which the card deck can be accessed. Once that's done, you can make and you should be set. Put make the images accessible at IMGURL, and install build/HSetHTML.cgi in your cgi-bin directory, and you should be off and running.