Centers are the linemen that have to let every other lineman know what he is doing. They have to be smart and make good calls in the blocking schemes. They touch the ball every play like the quarterback and are relied on to give good snaps to the quarterback. Centers need to hold their ground and drive back big defensive tackles. They have to be able to recognize inside blitzes and stunts and help out the other linemen.
A prototypical NFL center is at least 6'3'', has excellent feet, long arms, great strength, good hand placement, keeps low, is smart, takes good angles to get to his man and can move. This year's class of centers is better than those in years past.
Here are my Top 10 centers for the 2011 NFL draft.