This is a design for an open-source prototyping shield for Arduino Uno NG, Diecimila, Duemilanove. It has tons of cool features, to make prototyping on your Arduino easy.
Reset button up top
Lots of GND and +5V rails
DIP prototyping area makes it easy to add more chips
SOIC prototyping area above USB jack for up to 14-pin SOIC chip, narrow medium or wide package.
A 'mini' breadboard included
Extra 6mm button