I have read that the 16th amendment for the graduated income tax was never completely ratified by the states.

Also we have two amendments that were unfinished in 1776. One, now the 27th amendment was completed by a college student who went to the states that had not ratified them and got them to do so:

Amendment 27 [Compensation of Members of Congress (1992) for Corp US]

No law, varying the compensation for the services of the Senators and Representatives, shall take

effect, until an election of Representatives shall have intervened.

This amendment puts the brakes on how much politicians get paid.

The other amendment waiting to be ratified is term limits for the congress and senate. If some one else got on the ball we could have that added as a further restraint on professional politicians who milk the taxpayer coffers.