This board uses a relatively new boost converter chip from Texas Instruments: http://www.ti.com/lit/ds/symlink/tps61322.pdf

It has several noteworthy advantages:

1. Quiescent current of 6.5uA.
2. Relatively low cost compared to comparable chips.
3. Very high boost efficiency, even at low currents (see chart in photos section). In fact, in this metric it by far outperforms all the other chips that I'm aware of.
4. Low part count, which means faster and easier assembly.
5. Nominal minimum input voltage of 0.9v. On the one I tested, the minimum was actually lower at 0.79v from a cold start.

In this project I'm using the TI boost chip with a 3.3v fixed output, but a simple substitution of another chip in the same series will produce 5v, or other fixed voltages depending on the chip used.