At the World Maker Faire this past September, I had the privilege of meeting several representatives from a new open-source hardware vendor from France, Snootlab. They have a very interesting range of shields and other boards, soon to include the Zigduino. We now carry four of what I think are their most interesting and unique boards.
The Rotoshield is a motor drive shield that uses the L293 to control up to four brush DC motors or two stepper motors. There are lots of shields on the market that fit this description, but the Rotoshield has some special sauce in the form of a MAX7313 I2C port expander. This allows it to use only four PWM outputs and the I2C bus for control. It also gives the shield eight additional 50 mA PWM outputs for controlling LEDs and the like. These lines are also available to use as GPIO. All of this is handled by Snootlab's Arduino library for the shield, snootor.
The board can be powered off a standard ATX hard drive power connector, which is a nice convenience for many projects.
While we haven't had these shields in house long enough for me to try this, I suspect you can drive the PWM inputs of the motor drivers with the PWM outputs of the MAX7313... giving you a motor shield that you can run off a single I2C bus. That puts the Rotoshield head and shoulders above other Arduino motor shields on the market.
This board packages a MAX7313 and support circuitry in an extremely convenient package for driving LEDs and similar loads. Each of the sixteen channels can sink up to 50 mA of current. It also fully breaks out the address selection jumpers of the chip allowing you to select up to 64 different addresses. That means you can put 64 of these on a single I2C bus for 1024 PWM channels. Each pin can also be used for GPIO.
Since it's a sink driver, you can combine it with our high side sixteen channel driver shield to drive large arrays of LEDs at remarkably low cost. For less than a hundred bucks, you can drive 256 individually addressable and dimmable RGB LEDs.
The Memoire shield is an SD card logging shield with a battery-backed real time clock for accurate time-keeping. It has a substantial prototyping area that makes wiring up the rest of your sensors straightforward. Like the prototyping areas on other Snootlab shields, this one uses square pads to make jumpering between adjacent circuits easier.
The Power Screw Shield is a prototyping shield with a couple of useful twists. First, all the signals are pulled out to screw terminals at the side of the board. This makes wiring up a larger project infinitely faster and easier. Second, like the Rotoshield, it has an ATX hard drive power connector for supplying power to both the shield and the host Arduino. A mini-breadboard also fits nicely inside if desired.