Awesome and very useful project! Will definitely recommend it to use.
None of the Java applets run (http://thevirtualheart.org/, http://www.falstad.com/mathphysics.html, http://www.world-of-fungi.org/Models/tropisms/index.html, http://Ultrastudio.org, seems that anywhere else). This is already not just a bug but a deviation from concept. Java must be first class in the Java-enabled browser.
There are no 4 star reviews.