BigDaddy is a program for monitoring servers. It is similar to Nagios, with the added benefit of also monitoring and controlling the crontab (or any scheduled application) across an entire fleet of servers. The application comes in the form of a daemon for monitoring and reporting as well as an easy-to-use Web-based GUI for controlling monitoring, viewing timelines of incidents, filing incidents and graphing statistics. The application is extensible with any sort of monitoring module and notification is based on a five step escalation process.
Bobo Ratio is a one-to-one Web traffic trading script. It trades unique links with a one-to-one ratio. It uses the filesystem to store its data, so no database (i.e. MySQL) is needed. It is modular and easy to set up and use. It is simple. People send you traffic and you can track that and choose to send it back.
dm.KittenAuth implements a CAPTCHA validation solution using groups of images and associated questions. It can generate a form to let a user pick images for one or more groups of images stored in a MySQL database. The user must pick the right images according to the questions associated to the group of images being presented.
SVNBot is a program written in PHP that constantly runs in the background (or foreground, if desired) and monitors your SVN repository (or part of it). When it notices the repository has changed, it notifies everyone on its jabber contact list providing a quick overview of what has been changed (in a format similar to the 'svn log -v' command).