Open Turing is an open source fork of Object Oriented Turing 4.1.2 for Windows. It is up to 50% faster, includes new features like 3D support, and is constantly being improved.
To celebrate the 100th anniversary of Turing's birth, a team of geeks from the Netherlands decided to explain to the world just what the heck a Turing machine is--by designing and building one of out Lego. Check it out: