Some-time ago, Justin Wyatt approached me with his design for a stamp-sized Arduino board; several revisions later, I'm proud to introduce the DuinoStamp
The Duinostamp is a convenient breakout board allowing you to easily embed an Arduino compatible environment into your project. The same size as a 34-pin 0.600" DIP, it's easy to incorporate into bread-boards, perf-board, or PCBs. It contains all the components and connections you need, without including costly and large extras.
These are available as a full kit (just under 10USD) or a bare PCB (just over 4USD).
Questions, comments, whatever, bring them on.