For a period in time I was involved with the development of AniDB, a database of Japanese cartoons similar to IMDB. My main project there was developing the Signature server, a service that makes dynamically generated forum signatures using on a custom templating language. The signatures can display a lot of data such as which series the user is currently watching, recent votes and reviews, etc.
The initial version of the SigServer was released 25th November 2007 and has since served over 100 million signatures. It is written in PHP backed by PostgreSQL. Signatures are written in an XML-language. Simple data processing like rudimentary if-statements, truncation and similar is possible using a custom DSL. The DSL is a horrible mess of inconsistency and weird edge cases, but at the time I was very proud of it.
The main AniDB website is written in Perl, also backed by PostgreSQL. I did minor features and bugfixes on the website itself. Today the website has over 700,000 registered users and indexes over 10,000 different cartoons.
Due to lack of personal interest and time I left the project somewhere in 2011 to pursue other things.