RoundCube Webmail is a browser-based multilingual IMAP client with an application-like user interface providing full functionality like...

The TBSource code contains the basic components needed to build a private ratio based Bit-Torrent tracker. Originally based on the ByteMonsoon source, TBSource has easily become the most commonly used core for many of the private sites around today.

A PHP/mySQL-based server status monitor. Features include tracking services on multiple hosts, easy to use admin panel, e-mail and SMS alerts, SMS querying, tabular and graphical statistics, and highly integrable classes.

URL shortner.

Open Source Shop Script

Trellis Desk boasts an impressive set of features that will simplify and expedite the customer support cycle at your business or organization -- and you'll never have to pay any license fees to use it.

Ptwix is a PHP/AJAX web component to show tweets on web pages. With ptwix people can follow your twitter account directly in your site.