USB 2.0 Host Shield Module for Arduino (Works with Official Arduino Boards)

Pros: This USB host shield is exactly like the Italian (official) USB shield, and can effectively turn any Arduino (UNO, duemilanuove, Severino and Mega) into an ADK, offering USB host capabilities to your arduino project. It is very well built, leaving nothing to desire when compared to the more expensive Italian products. It works flawlessly with the stock Arduino USB libraries, and any project meant for the ADK will work with this shield. The ADK examples that come with Arduino 1.0.1 work with this shield.

Cons: It could and should be a little less expensive. It is more expensive than an UNO R3. The stackable header pins are extremely long. I had to trim mine a little with a Dremel tool.

Other: It is a very good addition to any arduino collection. It broadens quite a bit the possibilities of the project.

Pros: This is the revised version of the USB Shield, using more powerful communication interface and works by just attaching it on top of your Arduino board. The example libraries work, for example you can plug a USB mouse and read the movement and button presses by Arduino.

Cons: Price is a bit too high for the components it is built from.

Other: If you want to control USB slave devices from Arduino, you need a USB Host shield. Note that only a handful of device types are currently supported by the available libraries, but if yours is included, get this one, unless you can find similar for cheaper.