I posted some information about sideways layout (like the Seeedstudio's Xadow does it) in the
http://forum.tiny-circuits.com/index.php?topic=180.0 thread which may be of interest...
As for vertically stacking... (sorry for some duplication from the other thread)
The connector used on the Tinyduino is 2x16 pin connector for 32 signal lines. To accommodate the tiny profile of the Tinyduino and its mounting holes, a configuration with two 0.3 mm pitch 33 pin FFP/FFC flat cable connectors (such as the YLL-U or YLL-D SERIES), stacked one behind the other, with the second mounted taller (higher) then the first, should do the trick. Obviously, 2 different height FFP/FFC connectors would be needed.
A variant configuration for stacking.Pros:- Eliminates height restriction.
- Allows fat payloads between boards.
- Additional PCB board layers would not be needed.
Cons:- Extra connector does take up precious PCB real estate.
- Cable bulge makes stack wider.
- Cables can be a bit touchy to shifts and movements.
Please pardon the ascii figure diagrams.
Top View of staggered/stacked FFP/FFC configuationo - mounting holes
[ - First low connector (closer to the edge) FFP/FFC Connector for downward connection
[ - Second high connector (further in and taller) FFP/FFC Connector for upward connection
-------------
| o o |
| [[ |
| o o |
-------------
Side View of staggered/stacked FFP/FFC configuation daisy-chained with flat cables ^ - connector (high connector) for upward connection
^ - connector (low connector) for downward connection
|- - Cable
NC - No Connection since it is the top or bottom of the stack
3 Tinyduino Shields with FFP/FFC connectorsNC ^ (high connector)
|----^ (low connector)
| ---------------------- (Top Shield of Tinyduino Stack)
|
<Fat Payloads in between boards>|-------^ (high connector)
|----^ (low connector)
| ---------------------- (Middle Shield of Tinyduino Stack)
|
<Fat Payloads in between boards> -------^ (high connector)
NC ^ (low connector)
---------------------- (Bottom Shield of Tinyduino Stack)