Hi All. This is bit of a repeat but I'll post it here in the correct area so people can find it.
My company Robot Power has released our high-current motor control shield called the MegaMoto. This unit is capable of 13A continuous and 30A+ peak (couple of seconds) over a 7V-28V range. The MOSFET power chips are fully protected against thermal and current overload faults. A current sense voltage for each half-bridge is available and can be connected to any analog input pin.
The retail cost is $59.99 USD. These are in production and shipping now. Reseller or volume purchase inquiries welcome.
The unit can be configured as a single H-bridge or dual independent half-bridges. Jumpers are used to select the Arduino pins used for Enable and PWM. Up to three MegaMotos may be independently controlled by one Mega328-based Arduino. Independent control of up to six half-bridge circuits allow brushless and stepper motors to be controlled as well as brushed motors. Other loads such as lights and solenoids may be controlled as well.
More info is available here: http://www.robotpower.com/products/MegaMoto_info.html
I'll answer questions here as well as off-line