Adafruit Proto Shield for Arduino Unassembled Kit - Stackable - Version R3

This prototyping shield is the best out there (well, we think so, at least), and now is even better with Version R3 - updated for the most compatibility with just about all the Arduinos! It works with UNO, Mega, Leonardo, NG, Diecimila, Duemilanove, and compatible Arduinos. Yun's and Arduino Ethernets have a chunky Ethernet jack that gets in the way of stacking, you can use the stacking headers included and it will work, just doesn't sit nice and flat. https://www.adafruit.com/product/2077