Wolfram Demonstrations Project

The Wolfram Demonstrations Project is hosted by  Wolfram Research, whose stated goal is to bring computational exploration to the widest possible audience. It consists of an organized, open-source collection of small interactive programs called Demonstrations, which are meant to visually and interactively represent ideas from a range of fields. At its launch it contained 1300 demonstrations but this has grown to over 10000. The site won a Parents' Choice Award in 2008.