These DC motors have a gear box already built in, and wires attached, so they're super easy to use:
We also have a wide range of matching wheels:
Other accessories are available, check the Adafruit shop for "TT Motor" items for the wide range of add-ons available.
If you need a motor that is very compact (but not very powerful) these DC-in-servo-body motors can do the job:
Which can be used with this wheel: