Dave Prochnow writes on PopSci:

Every AVR programmer worth her weight in ATmegas knows about the AVR Butterfly–a ridiculously low cost ATmega169 demonstration and evaluation kit. Lamenting the lack of such a kit for the ATmega168 drove me to design my own demo/eval kit for the Arduino microcontroller family. This project became a compulsion that cost three complete redesigns, five destroyed ATmega168s, and hundreds of hours of point-to-point wiring. The result was Polyphemus–an ATmega168 demo kit that you can build from your own spare-parts box.

Polyphemus Demonstration and Evaluation Kit