Unfortunately, Sun's security model for applets was always a bit flawed, and Oracle has let it get to the point where applets are unadvised to the point of being obsolete. Which is a shame, because some of these are kind of cool.
They will probably not run in your browser. However, if you run appletviewer (by having the Java JDK installed) you can probably run them by entering the URL of the page they're on.
Java source code only, licensed under the GPL. A brief README accompanies.