Some of the applets are created almost 8-10 years ago with JDK1.0.2.
However, there are many recently generated simulaton were build by a tool called Easy Java Simulation.
You can find out article about EJS from [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=95.0]Easy java simulation (Download and related informations)[/url]
You can find a book about EJS from [url=http://fem.um.es/]Paco's web site[/url]. (Author of EJS)
And you should be able to download all the simulation when you login to the system.