I've used the Delta.
It gives a between the legs, under the seat view.
It works after a fashion to give you an idea of what's behind you.
The biggest weakness is that it goes out of alignment very easily, that and; you have to give it your attention in order to interpret what it is you are seeing as the POV is odd.
Overall, it's not very practical.
Last edited by jwbnyc; 06-25-06 at 11:40 AM.