I finally got around to documenting one of the I2C boards I had made: a simple 1-3 splitter.

Blog post: http://smokedprojects.blogspot.com/2014 ... r-pcb.html (http://smokedprojects.blogspot.com/2014/02/daisy-chainable-i2c-splitter-pcb.html)
Github: https://github.com/t0mpr1c3/I2C-splitter (https://github.com/t0mpr1c3/I2C-splitter)
I'll eventually get around to add more boards to this thread as I write them up. The design thread is here. (http://http://dangerousprototypes.com/forum/viewtopic.php?f=19&t=6003h)
I2C level shifter with SOT23 voltage regulator.

Blog post: http://smokedprojects.blogspot.com/2014 ... ifter.html (http://smokedprojects.blogspot.com/2014/02/daisy-chainable-i2c-level-shifter.html)
Github repo: https://github.com/t0mpr1c3/I2C-level-shifter (https://github.com/t0mpr1c3/I2C-level-shifter)
Cool idea! It might be nice if one of the connectors was moved in more, so you could chain boards together with no gap between the boards. Like this:
http://https://www.tindie.com/products/FriedCircuits/led-matrix-link/
Maybe move the connectors to the back side so the SMT components on top don't get in the way.