Which, if any, of the automatically generated stub & skeleton class files does one need to include in a JAR file to be used when creating stand-alone clients? (I would like to create a client-side jar file which contains only the class files actually needed by the client.)

The answer is really not that generic as one may like to believe! Basically what a client needs to invoke the services of an EJB layer are:

• locate the home interface (using a JNDI SPI) & invoke methods of the bean instances (over IIOP). Depending on the vendor (e.g. IONA builds JNDI over CORBA) the actual files will vary. You have to check with your vendor.
• definitions of serializable objects that are returned to client due to network considerations (instead of object references).

See also:

• What classes does a client application need to access EJB? (hmm, kind of redundant, oops :-)