Here's a list of various unofficial Wesnoth related tools that somehow relate to the game or it's community. Please keep in mind that they are not in any way supported by or linked to the Wesnoth staff.
If you have developed some kind of tool that has to do with the game you're welcome to add it to the list. Don't forget to include a short description of what it does and who to contact.
Ladder of Wesnoth
LoW is an open source game ladder system adapted for Wesnoth that uses Elo to rate players in 1 vs 1 games. It's in PHP & MySQL and the core of http://ladder.subversiva.org. Contact eyerouge (a) eyerouge (dot) com to help code.
Open source script that parses the results of Wesnoth Replays, making it easy to keep statistics of all games played, kind of like battle.net but better. It will be implemented in the Ladder of Wesnoth but will work on any site, stand alone as well, and could easily be implemented in existing sites. Contact eyerouge (a) eyerouge (dot) com if you have questions.