In another thread, VonSzarvas convinced me to purchase several Circuit Overlay Boards. At first I was a bit reluctant, but the idea eventually grew on me.
Prior to my purchase, it was clearly obvious that these boards did not have much prototyping area, but I did not think that I need a lot of prototyping. After receiving these boards, I have put a little thought into them. Without going into a bunch of mumbo-jumbo, I now believe it may be beneficial to create another variation of these Circuit Overlay Boards, to make them "stackable". By making them stackable, it would further reduce the available prototyping area on a single board, but by stacking them, a person could have unlimited prototyping space and still be able to access every single pin.
That being said, now picture this.... The current Circuit Overlay Boards have three sides for headers which can be pressed into accommodating breadboards. These header pins connect to outlying holes for connection to power, ground, I/O, D/A, and A/D. My recommended variation would include a third set of interconnected holes to the inside of the header pins, which would make these boards "stackable", by alternating headers and header sockets for each board stacked, meanwhile still allowing access to all of the connections, through the addition of the third interconnected holes.
EDIT: Think of the "stackables" as a multilayer PCB