The challenge board project aims to be an open source ladder system that can be used to run any number of competitive events. If you can compete against a single an opponent, you can can have a challenge board.
Competitors can move up and down on the board by playing amongst each other and submitting the results. Standings are currently calculated using a standard Chess ELO algorthym.
ASP.NET 4.5
.NET 4.0
SQL Server
Recaptcha keys: http://www.google.com/recaptcha. Recently I've needed to add protection against spammers, so Polite Recatpcha is now being used. You can develop on localhost, but moving to production will require a set of keys.