Add to list: Curl fingers like around a tube of pepperoni and slide up and down 4 times. The salute to the rider types that don't wave back, after the fact of course.
A new I just came up with: the quick duck/stay down behind shield means crap flying off the vehicles ahead or low flying birds, so watch out.
American Sign Language
Pretty
(beautiful, beauty) The right hand, fingers closed over the thumb, is placed at or just below the lips. It then describes a counterclockwise circle around the face, opening into the '5' position, to indicate the whole face. At the completion of the circling movement the hand comes to rest in its initial position, at or just below the lips.
Bed
The head is tilted to one side, with the cheek resting in the palm, to represent the head on a pillow. Both index fingers, pointing down, move straight down a short distance, in unison (the two front legs of the bed), and then are brought up slightly, and move down again a bit closer to the body (the rear legs).
Sandwich
The fingers of the upturned right hand are tucked between the middle and third fingers of the left hand, whose palm faces the signer. The motion may be repeated.
Kiss
With fingers touching their thumbs, both hands are brought together. They tremble slightly, indicating the degree of intensity of the kiss.
Knob
The signer pretends to grasp and turn a door knob.
Phone Number [duh]
Finger the numbers she uses to track you down and turn you into the police for sexual harassment on a public highway.