Where can I download the [netscape.javascript] JSObject class from to compile my applets that use LiveConnect?

The Java Plug-in 1.3 ships netscape.javascript in a JAR file called JAWS.JAR. To compile an applet which uses JSObject, just add JAWS.JAR in the CLASSPATH before compilation.

If you don't have the Plug-in, but do have a Netscape browser installed, you can add the java40.jar file that comes with Communicator to the end of your CLASSPATH (or extract the netscape.* classes from there).