I do this regularly, though most of the work so far has tended to be much
 more centric on web based applications.

 >> 1. A database
 >>     Java world: Oracle, MySQL or another relational DB of your choice

 MySQL

 >> 2. Some way to persist domain objects and manage transactions
 >>     Java world: entity EJBs, JDO, hand-coded DAOs, O/R <censored>
 >> mappers, etc

 Kansas has been maturing wonderfully for my purposes for this.

 >> 3. An RPC (remote procedure call) mechanism for communication between
 >> the front-end and the back-end (assuming that the front-end is a
 >> thick GUI).         Java world: session EJBs, servlets

 drb.  Works great.

 >> 4. A thick GUI
 >>     Java world: Swing

 TK, Qt, Fox

 >> 5. A Web GUI
 >>     Java world: JSP, XSLT, XMLC and all the other stuff

 I've use Iowa very successfully for this every day for a couple of years.

 >> 6. An asynchronous communications infrastructure
 >>     Java world: message-driven EJBs

 I am using Drb/Rinda/Tupleserver pretty effectively for this.  No problems
 with it at all so far.

 Kirk