Pylist is a free and open source directory software that you can use to create your very own web directory, similar to Open Proxy List, Ultra Directory or even Yahoo. It uses a database backend and can scale upwards without suffering a significant performance penalty.
The need to Pylist came about due to the limited choices people have when it comes to free and open source alternatives to popular web directory softwares. Pylist started as a set of scripts and soon turned into a full-fledged listing software.
For a full list of features, check out the Features page.