This shield from Sparkfun (replacement for DEV-10305) DEV-10618 allows you to use a computer power supply (or other power source) to use your Arduino to switch high current. With RFP30N06LE MOSFETS, you can easily control a lot of current directly from your Arduino.

The board provides 6 PWM outputs via screw terminals. Check the datasheet for the MOSFET under the 'Downloads' tab for full specifications on how much current this board can handle.This board is a very easy way to start using MOSFETS for your next high current project.

A protection diode has been added to the power input on this version of the board.

Note: If you want to stack another shield on top of this one, you will want to double-up on the stackable headers to clear the MOSFETs.