Scratch - Scratch is the programming language & online community where young people create stories, games, & animations.
Scotty - Scotty is a Haskell framework inspired by Ruby's Sinatra.
Cyberix3D - Free online 3D Game Maker. Make your own 3D games online!
Yesod - Yesod is a development tool used to create highly efficient websites and web applications from the ground up. Yesod includes almost everything you need to build a website, from templates to routing and execution. Read more about Yesod.
Open 3D Engine - Open 3D Engine is an open-source 3D game development engine in real-time.
Happstack Lite - Happstack itself is a web framework created in Haskell. Happstack Lite is an easier version to use that can import features from the heftier version if need be.