Looking to run some motors with an Arduino? This Motor shield from Adafruit will make your life a lot easier. Adafruit Motor/Stepper/Servo shield can run up to 4 DC motors and 2 Stepper motors. Mount it on top of the Arduino Board(Uno, Leonardo or Mega), and you get a powerful Robot driver.
It is powered with TB6612 dual H-Bridge driver that has a low voltage dropout as compared to L29D and has built in flyback diodes. Also there is dedicated PWM driver chip which handles all the motor and speed controls over I2C. Only two pins (SDA & SCL) are required to drive the multiple motors, and since it's I2C you can also connect any other I2C devices or shields to the same pins. You can also stack up to 32 of these to drive up to 64 Stepper Motors and 128 DC motors.Here's a full list of features: