I picked up a really cool accessory for my 12-gauge semiauto yesterday: a HI VIZ Magni-Hunter sight.
The Magni-Hunter uses a shroud around a light pipe to eliminate problems caused by cross-dominant eyes. It fit the rib of my Browning Maxus perfectly, and the light pipe is completely invisible to my left eye, which means I can stop taping over the left lense of my glasses at the skeet field. I haven't actually shot with it yet, so we'll see if it improves my results, but I can vouch that the shroud works as advertised. It sure looks promising to me.