Last night I finished assembling and uploading a sketch over USB to Demiduino. At half the dimensions of an Arduino, Demiduino is a small, portable, and affordable Arduino compatible with the Leonardo bootloader.
Digital pins 0-7, Analog 2-5, and a RST, V+, and GND pin are broken out to two rows of pins, maintaining about half the pins in a familiar shape and organization. A JST connector for LiPo batteries like the ones available through SparkFun and Adafruit and an MCP73811/2 charger circuit makes the Demiduino well suited for portable applications. On the back, I've also included CR1225 clips for ~3v3 power from easy to find coin cell batteries, and a power switch to save battery life.
I can make an individual Demiduino with about $12 in parts. With a 32u4 for USB support and more SRAM than a stanard 328, and a means of charging lithium batteries, that makes it a pretty good price for me. I understand AVRdude isn't real happy with 32u2s, but I hope to make an even cheaper and prettier board using that chip soon. Without easily breaking out I2C or SPI, I don't consider this board nearly as functional as the inspiration I drew from to make it. (Paul's Teensy, or Adafruit's 32u4) Rather, this might make a nice alternative to SparkFun's Lilypad Simple if you don't need wearable features, and it's what a few of my friends would like too. Also it has a pretty UV purple LED. My schematic and board files don't match, but I've uploaded a screenshot of the schematic anyways. Enjoy!
I'll be at Townshends (NE) probably all this evening working on C homework. I'd be happy to show you my board if you're around! I have a hoodie on that matches Laen's boards. I like this hoodie, for that specific reason.