The lack of a 3.3v line on TinyDuino makes it very difficult to develop code for sensors that require 3.3 volts because the levels shift to 5v when you plug into the USB port. However with the distributed regulator & level shifter components already in use by the tiny boards it would be easy to create boards specifically for I2C  sensor connection, that stabilized these voltage swings.

This would be really great for those of us trying to run from things like AA battery packs, that change voltage significantly over time, as we run into the same problem with sensors that can not withstand the voltage swing. Yes, I can go hunting for a voltage regulator, and a level shifter, and cobble something together. But if Tiny Circuits sold a $15 board just for this purpose, I would buy it in an instant, as I want to spend my time making the sensors do something useful, rather than spending my time just getting them running.

Essentially you could just take and existing product,  like the light sensor board, leave the other components in place, but remove the light sensor itself, and replace the pads with through hole connections near the edge of the board. I think the regulator you are already using would supply most of the I2C sensors out there, but you could also make one with a beefier regulator if people asked for it. My guess is that if you left the inbound VCC, GND, SCL and SDA ports already on that board, there would be plenty of customers for this regulated I2C sensor board for other battery run systems, outside of the tinyduino ecosystem, because it would save them a lot time and effort too.  And, no matter what sensors people are using (in my case high range MS5803 pressure sensors), Tiny circuits generates a sale.

Do similar modifications to the SD card board, and you would have an SPI sensor development board to sell as well, although that one would need the "inbound" lines broken out for the external market.

I really think this kind of generic sensor board could change the Tinyduino system from one with a 3.3v limitation, to one of the easiest systems to work with, and opens access to all the I2C/SPI sensors out there that have limited voltage tolerances.