You can do it with a PWM - which varies the frequency of the 60hz power from the city. You'll likely find that they cost more than a new DC motor and controller, usually, though.
This question comes up quite often and sadly the short answer, like Don said, is no. Induction motors rely on the frequency of the AC power coming in to set their speed. Dimmer switches and router speed controllers don't vary the frequency, just the voltage. With induction motors, a drop in voltage means it will pull more amps which leads to more heat or blown circuits or worse - a smoking motor. Routers and other "universal' motors actually rely on the voltage to set their speed - most of them actually run just fine on DC current, too - which can't be said for induction motors.