Ack...I've never heard of someone actually using a cage...but there is something called "collaring"...but that can be very subtle...a necklace or ring or bracelet. But even that's taking it past dom/sub to dom/slave...very very few take it that far.
Heather...there's always a chance that one would run into a guy who was a dick and genuinely enjoyed hurting and humiliating women...but that's not the way it's supposed to be....a dom should cherish and adore his/her partner, and would ideally make said partner feel as if he/she did.