CrossRoads, you should change your nickname to "SolutionMan" or "TheManWithTheSolutions" or something 
I's stretching my mind to understand the boards you presented here and I think I'm starting to realize how deeply convenient they are for this LED cube project!
I am seriously thinking about requesting an LED support board as it would be much more elegant than the perfboard solution I had in mind and it would save me a lot of time. I can't use it for the 4x4x4 test cube because with that one I plan to include variable resistors connected in series with the 82 Ohm resistors in order to experiment with how much current is exactly needed for the LEDs. With this approach I'll be able to determine the exact resistor values which I will use for the big cube (8x8x8). So, if my 4x4x4 cube will prove to work fine, I'll have to order such an LED support board from you. I like the 13.2 x 10 cm version better because it's less crowded.
As for the other board, which is meant to hold the shift registers, it's also very tempting. There are quite a few things I don't fully understand about it yet. For example I suspect that the IC1 (the big IC) on it is a microcontroller which is meant to replace the Arduino. If that's true, I probably don't need most of the left part of the board. But the bigger part, the right part, is a convenient way to hold the shift registers. Another thing I can't see is where I'd connect the MOSI, SCK and SS signals coming from the Arduino.
I see that you design very nice boards, which you also sell for more than correct prices. Do you by any chance happen to have a version of the shift register board specifically designed to work with the Arduino? If I understood things correctly, that would make the board smaller because it would leave out the left part of it. It would also be more elegant.
Final question: Did I understand correctly that these boards that you presented are completely naked, I mean there aren't even pin headers soldered to them, they are just the boards, and nothing else?
Thanks,
Andras