Getting back to the subject of lower power data logging, I picked up a FRAM chip from Mouser to fool around with and since I've never soldered an SOIC-8 package, I figured it would stretch me a little. Turns out SparkFun's SOIC-8 BoB makes it really easy, the vias in the middle of each pad are a good idea to me. So this little chip is impressive from a low power standpoint. At idle it draws 1.2uA. During writes it draws around 3mA so it can easily be powered from a GPIO which lets you turn it off when not needed. It takes 1ms from power up to be able to write data and I am able to read and write at speeds of 2.42us per byte (3.3Mbps). Since FRAM writes at bus speeds, you can depower it as soon as you finish writing to the SPI bus. Not sure how much data you log, but FRAM is certainly very interesting.