ActiveHs is a Haskell source code presentation tool, developed for education purposes.
User's Guide: http://lambda.inf.elte.hu/fp/UsersGuide_en.xml
Developer's Documentation (partial): http://lambda.inf.elte.hu/fp/DevDoc_en.xml
The software is in prototype phase, although it already served more than 700 000 user requests at Eötvös Loránd University Budapest, Hungary.
Note that this software has many rough edges; you are welcome to work on it!