Ok, this is a revolutionary GMod idea.
You know Battlefield 2?
And how you can stand, crouch, and lie down?
Well getting down on the ground is called being prone, and i think that this could be a major dig in the GMod world, such as having the ability to squeeze through smaller vents and get into certain props [like the headcrab kennel] and maybe allow for more finite construction techniques in non-noclip servers.
So how about that?