A .NET API, written in C#, for the generation and visualization of tournaments. Also provides an easy-to-serialize "pairing" data structure for saving tournaments to a database or XML.
TournamentApi is made for the purpose of running all sorts of tournaments and serializing them to a database. Originally developed for the LAN Lordz LAN party.
Includes a plug-in infrastructure for easily adding tournament types.
Here is an example of it's use, from the StackOverflow Battleship Competition: