Arduibug
From Hackstrich
The Arduibug is a small adapter board that 'wedges in' between the chip and the socket on the Arduino Diecimila or Duemilanove and allows use of a Debugwire in-circuit-debugger. The normal Arduino board does not allow this due to other components on the /RST line. The board is completely passive, the only components are sockets/headers/switches.
Project Status
PCB design complete, initial physical validation looks good. BOM on file at Digikey, just need to order prototype boards and parts now.