com is a TOPS-20ish TALK (aka LINK) for UNIX. It basically links multiple TTYs together, though differently than in ITS or TOPS-20. It supports multiple public/private rooms, chat logging and automated cleanup.com runs on SDF.org
A quick reference guide for PHP, with functions references, a regular expression syntax guide and a reference for PHP's date formating functions. As of 28/6/14, the cheat sheet now includes popup links to the appropriate PHP manual pages.