I've been kept from boarding because a small plane was overweight. There is no compensation and it's a bummer.
In 2003 a commuter plane crashed in Charlotte, NC because it was 400-1,000 pounds overweight. There was some type of maintenance problem that contributed to the crash, but absent the excess weight it likely would have been okay. That's really not much margin for error! At the time it was noted that the weight allowance for men and women had not been changed for many years and that people had gotten fatter. I really don't think the deviate from the standard when calculating weight, so the star of My 600-pound Life would be marked down as a 140-pound woman.
Whenever I see people yell or fuss at counter agents over a safety cancellation I always thank them. Be glad they yanked you off the plane!