The new 45 Degree viewfinder by Inon for Nexus D200,D80,D2x, Canon 5D and 1DsMark2.
It can also rotate for vertical position shooting. The 45 degree angle helps you keep bubbles out of your vision and allows you to get the camera at much lower shooting angle. It gives you the freedom to shoot on the flat ocean bottom while still being able to see through the finder.
The Inon 45 degree finder is a optional accessory and has to be installed by USA Nexus factory in the USA