References:

Solenoids:
http://www.electromechanicsonline.com/product.asp?pid=25

Motors & Gears:
http://www.servocity.com/html/168_rpm_gear_motor.html http://www.servocity.com/html/32_pitch_acetal_hub_gears__1_8.html
http://www.servocity.com/html/gear_racks.html

Relay Switches:
http://sigma.octopart.com/13005/datasheet/Omron-G5V-2-H1-DC5.pdf

Keypad:
http://www.eecs.umich.edu/courses/eecs373/Labs/devices/keypad%20spec.pdf

Character Display:
http://www.eecs.umich.edu/courses/eecs373/Labs/devices/optrex%20maufacturers%20spec.pdf