This is a design for an open-source prototyping shield for Arduino NG/Diecimila. It has tons of cool features, to make prototyping on your Arduino easy. Shipped with fully assembled.

Features:

Reset button up top
ICSP header
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
Compatible with: Arduino Duemilanove, Arduino NG, Arduino Diecimila.
Tutorial using Proto Shield for LED
 

Working with: Arduino Uno, Arduino Mega and Arduino Duemilanove.