The Drupal community uses IRC extensively for collaboration and community building. A permanent and ever-helpful fixture of the official #drupal-* IRC channels, and in the Drupal community itself, is the humble Druplicon bot. Druplicon is a Drupal-based IRC bot that was created in 2005, and is still going strong as part of the Bot module for Drupal.
Bots like Druplicon do a lot of nice things—they can remind people of things after they were away for a while, they can store facts, track karma, throw people virtual beers, store and retrieve helpful facts, and relay important information. For example, when a build fails in Jenkins, a bot can post a message in IRC. Similarly, if a server goes down, or is under heavy load, the bot could post a message.
What if you want your own bot for a different IRC channel? Drupal's Bot requires an entire Drupal environment to run, and while the bot is not too heavy on resources, an always-connected, efficient and pluggable bot would be better off on its own. And in PHP-land, there's just such a bot. Meet Phergie, a PHP IRC Bot.