The Astanda Directory Project was fullly active until a few years ago, not sure exactly when it disappeared. It was described as the only one of it's kind, written in php with MySQL databse, and was apparently capable of indexing thousands of sites without any drop in performance.
The home page displays categories and latest links added, and includes an 'add url' button for users to submit their own sites. These can be added automatically or upon admin approval depending on the settings in the admin panel.
Admin can log in and adjust many of the features of the site, such as depth of crawl, indexing options, add categories, spider url's etc.
The project was created as an alternative to the DMOZ project, and it's hard to understand why it has died a death, the website still exists but simply asks for a log in when you arrive, and show's nothing but a blank page.
As a search engine, it was quite an achievement at the time, and I'd love to know if it's salvageable. I have several versions of the same script and tried one out just before writing this article. It's a bit temperamental, but I do remember it worked well in the past. So either I've tested out an earlier version or differences in php and MySQL versions or even in apache (as it uses .htacces) are causing this behaviour.
There's nothing that can't be repaired easily enough and readers may like to test the script out for themselves. As soon as I didg out the other versions, I will link to them here.