I would like to have a single board to mount two shields side by side horizontally, that is good for wearable projects I think.

Just like this one, there is horizontal version and vertical version.
https://www.microduino.cc/module/view?id=53eb213a3f6ada00004fb0f4

With the ribbon cable shield only able to connect two boards up and down and not fix in position.

Up. I want this as well.

I would like to see more sensors:

Barometric Pressure/Temperature/Altitude Sensor
Luminosity/Lux/Light Sensor
RGB Color Sensor

Or can I use TinyDuino with these:
http://www.adafruit.com/products/1603
https://www.adafruit.com/products/439
http://www.adafruit.com/products/1334

I want make a tiny exposure meter and barometer for forecast weather, and color sensor to measure color temperature.

And is it easy to add infrared emitter?