Here is a picture of damped sprocket. It has rubber disks on both sides of the sprocket and damping is only for the noise generated by chain, doesn't help a bit with vibrations.
Time to change my sprockets and chains. Ran across this thread while doing research. Thought I would reply and "pare down" the info in this thread: Stock set-up: 17/42 Rear tire rotates .40476 turn per 1 front sprocket turn 16/42 combo Rear tire rotates .38095 turn per 1 front sprocket turn 17/45 combo Rear tire rotates .37778 turn per 1 front sprocket turn And someone mentioned a 16/44: Rear tire rotates .36364 turn per 1 front sprocket turn