In 2001, I developed a collaborative wiki-style application, Lucid Fried Eggs (Lucid). The application provided anonymous page editing, hierachies and graph-based linking, and stylesheet templates to provide various views of the information. All information was stored in a MySQL database. The application was written in PHP3. This hobby project was developed over a Christmas break (2 weeks) and consisted of about 2000 lines of code.
Like many open source projects Lucid development was discontinued once the developer was happy. Also like many good open source projects, the project was passed onto a new group of maintainers and continues development to this day. The new fork from http://Pantha.net is called TransLucid.
See the sourceforge page for more information.
Here's the 2001 code, lucid-0.096.tar.gz , which probably won't work due to differences between PHP3 and PHP5.
In 2001, there was a lot of activity regarding topicmaps, wikis, data visualization in graph-based structures. Lucid was integrated with Alex Shapiro's wonderful TouchGraph software and Ben Darnell's excellent ThoughtStream software. At the time, memes.net was devoted to cataloging a universal body of knowledge (now called crowdsourcing), very similar to wikipedia or everything2. Fortunately, Wikipedia gained much more widespread adoption.
My thanks go out to Andrius Kulikauskas from Minciu Sodas labs for his support and promotional efforts.