have been shown to cause this in some people
(since they are vasodilators)

Diltiazem (Cardizem)
Verapamil (Calan)
Nifedipine (Procardia)
Amlodipine (Norvasc)

These drugs are used for blood pressure.

Also histamine release from foods, can cause flushing, but it is typically more global than just the feet. (this is similar to Niacin flush)
This histamine flush or Niacin flush can be blocked by aspirin and bicarb.
If you can take aspirin, try an AlkaSeltzer....it works!