I recently moved my 18F4550 prototyping circuit from a breadboard to a simple PCB, to make it cleaner looking and more robust.  I just added the schematic+PCB layout to the 18F4550 USB Interface article; File format is Cadsoft Eagle 4.16.

 I also just recently experimented with a couple of new things with the PIC USB interface:  adding an additional endpoint to the microchip firmware, and interfacing that endpoint on the PC side as an asynchronous IN endpoint, which means that it gets automatically buffered, up to 100 packets.  Still requires calling a function periodically to see if there's any new data in the buffer, but I plan to do that in a separate execution thread, and set up an event/delegate system to the main code for a straightforward interface.  I'll try to put together an article soon about what it takes, because by the time you've jumped through all the various sections that you have to modify to add an endpoint in this case, you should get a pretty good idea of how things are set up, and somewhat of an idea of where you'd begin if you were trying to make more significant changes or additions.