Can someone tell me where I could find an incredibly small motor, preferably stepper but really just must allow reversal (at this point I'm thinking with some kind of SMD h-bridge like http://parts.digikey.com/1/parts/1571182-ic-dc-motor-driver-h-bridge-smd-an44065a-vf.html). Not too worried about power but it obviously can't be just a vibration motor.
Thanks!
One way to get a small motor is bying a small servo and just use the motor, or modyfi it for continues rotation (it already has the H-bridge on a small print)
Example:
hobbylobby.com, or maybe its hobby-lobby.com,
has lots of servos, and there are plenty of videos around that explain how to open them up to make them continuous rotation.
You could also browse the stepper motors here, see if any are small enough for your needs.
Stepper Motors & Drivers-Electronic Components and Accessories | MPJA.COM
Or maybe pull the motors from a dead inkjet printer, I think those are stepper motors as well.
Probably reuse the power supply board as well.
I think this is a trick question: it's impossible to find an incredibly small motor 
The least expensive and most readily available place to find a small DC motor is in a vibrating toothbrush.
Pololu has some very small motors and also gearmotors.
Electric razor, even smaller than a toothbrush. Yes it's a vibrator but all that is is an off-balance weight that can easily be removed.
incredibly small motor
Smallest motor I've come across is the one inside this solar powered car. These are fun to have around. I've had to order 15 already to keep myself, friends, and family happy. 
Motor measures about 5/8" long (including gear) by 3/16" round.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280696806814&ssPageName=STRK:MEWAX:IT
Lefty
Why "not just a vibration motor"? I've found these are the tiniest motors you can get, and surplus dealers often have a variety of them in stock:
Electronic Goldmine shows one with dimensions of .375"L x .2" square (although I think the plastic "square" around the motor is removable to make it even smaller!)
Pager/vibrating motors are ordinary DC motors with a small off-center weight crimped onto the shaft, but these can usually be removed pretty easily. For steppers, the smallest NEMA frame type I found (buyable by hobbyists) was from Pololu, but it doesn't come close to being as small as the pager motors.