Virtual Hideout published a review of the Zalman FPSGun FG1000 Gaming Mouse.

Quote from the review: "Looking at the FPSGun might give you the initial impression that it is some sort of Light Gun that you point at the screen. It is not. Instead, it regular mouse that somewhat resembles an inverted handgun. Thus, you hold it somewhat like you are gripping something, dare I say the handgrip of a "gun".
The bottom of the mouse still has to rest on a surface; you aren't expected to hold this in the air. Instead, you move the FPSGun around approximately the same way you'd move a mouse around, sliding it on a surface. (The bottom has mouse feet just like any other mouse)."
Read the full review on Virtual Hideout.