I have created two working systems for my university course, the first being my Server Status checker and the second being Wonderful Wiki, Wiki system.
Both these systems were created in PHP and are fully working. I will try and release the source code at some point for people to download and I may continue to develop the systems but in the foreseeable future these systems will just be archived and readily available.
Update: Please note, since I developed my dissertation; the server status checker, Twitter has removed the support for the authentication being used, so the demo may not work correctly.