Motor control

Control of a basic motor using Parallax Motor MInd B http://www.parallax.com/

or the Secret Drive kit from Solarbotics that fits INSIDE a servo http://www.solarbotics.com/products/k_smd/

or the bigger version Kit #13 - L298 Compact Motor Driver Kit from Solarbotics 
http://www.solarbotics.com/products/k_cmd/ which usable from 6 to 50V, at up to 4A total output current

For stepper motors parallax has the Little Step-U Motor Controller at $70 it can save a lot of time and BS2 computing time

EasyDriver v3 Stepper Motor Driver for stepper motors at http://www.trossenrobotics.com/easydriver-v3-stepper-motor-driver.aspx