A couple of interesting examples of navigation including use of Z axis.

Whitevoid:
Looks to be a company’s portfolio and it’s a recent FWA winner. One of the more fluid and usable examples of including the Z axis I’ve seen. As someone clicks into a navigation element it reveals the sub-elements in front of the higher level elements. This paradigm continues and the perspective is shown as such that you can still click the higher level items or click off in the white space to dismiss the current level.

Diller Scofidio + Renfro:
Another company’s portfolio. The mouse allows the user to manipulate space along Z axis by moving physically closer or further. The faster or slower the user moves the more momentum is given to the movement. There is also a solid feeling as the user progresses through each group of photos so they can almost count along as they pass through each group.

Let the experiments continue! I think our new found love of gestural interfaces is filtering into the web’s old mouse and keyboard paradigm.