I can't be the only rider who hates having a blind spot and having to turn ones helmet cladded head to see if it's safe to change lanes, especially in a split second situation. So having said that I fabbed up some custom blind spot mirrors...
When properly placed these completely eliminate the blind spot making for much safer lane changes, and riding in general. I've done this to my last 3 bikes and while they do take a little getting used to (that inner 1/3 of the mirror is pretty useless anyway), I will never ride without them.