Fingers are very useful things, they are. You can cross them, shake them, use them to poke people, and even flick people on the forehead with them! Depending on the finger used, they can be used to gesture various nonverbal communications as well:
Thumb: "You did it!" "Great!" "Yeah!"
Pointer: "Uh-uh" "Tsk, tsk"
Middle Finger: "Coise you!"
Pinky (in Japan): "My (usually improper) girlfriend/lover"
Fingers splayed in the middle: "I am a Trekkie"
Unfortunately, the ring finger doesn't seem to have much meaning by itself...