S&B does make some specialty loads with both rubber buckshot and rubber 12ga balls.
Shells like these used to be somewhat popular for police use, particularly riot and crowd control. Usually, rubber shot if fired at the ground in front of a mob in hopes that it will ricochet into the crowd and cause them to disperse without causing serious injury.
I would not use rubber shot in any circumstance that lethal force would not be justifed other than maybe for running off nuisance animals. The only possible place that I can see for rubber shot in a self-defense situation would be to immediately follow it with regular shot. By doing so, I could see someone possibly being able to claim that they tried using a non-lethal alternative before resorting to deadly force. It is, I admit, a far-fetched idea and I personally just load regular buckshot in my HD shotgun. I figure anything that needs to be shot probably needs to be shot with real buckshot.