easyGM is a toolset for GameMasters. It creates a virtual tabletop on which you can store information, roll dice, and create maps. It has lots of tools to begin with and can be extended using it's built in module system.
Math game where up to 4 students can play online against each other. By moving their figurines around a colorful pseudo 3D board, players answer math questions and can play tricks against their opponents. Client and server distributed under Affero GPL 1.