Stuff4Pi posted his ConvertPi, a Raspberry Pi GPIO full level converter & monitoring, in the project log forum:
I would like to introduce my first Raspberry board: a GPIO bi-directional level translator (3.3V <-> 5V):
– This is an in-between expansion board that you plug in the RPi P1 connector which gives a bi-directional level shifter for each GPIO (x 17)
– The board also acts as a monitoring as each GPIO has it’s own LED for visualization of its state. The LEDs are buffered meaning that they don’t have any influence on devices you may connect to the GPIOs
– Finally, there is a mini (micro!) prototype area with replication of the 5V GPIO
You can find project details on Stuff4Pi website.