Itching eyes are also significant. The first documented reference in English is in Othello Act 4, Scene 3), "Mine eyes doth itch, Doth that bode weeping?" It's not clear if this was one of Shakespeare's inventions or him recording a piece of common folklore, although it apparently appears regularly after then.
There are a number of other superstitions associated with eyes, for example with cross-eyes or those of different colours. Not so much for elbows though.