Cleveland, Ohio - "C" touching your right shoulder then left
Akron, Ohio - the "X" hand shape brushing the side of your chin
Madison, Ohio (my pitiful hometown) - Like government, but with an "M"
Columbus, Ohio - "C" shaken in front of your shoulder
Cincinatti, Ohio - "C" brushed under the chin
Mentor, Ohio - same sign as "bird"
Some international signs I know:
Paris, France - both hands with the 2 handshape face eachother and move in and up in the shape of the Eiffel Tower
China - left hand makes a "G" and right index finder taps it so it almost makes an "A" shape
Japan - make the sign for vagina and then touch your fingers to your thumbs like you're trying to pinch something
Australia - 8 handshape with palms facing down and flick middle fingers, like a kangaroo hopping (I love that sign)
Egypt - make a pyramid with the B handshape