linked-questions "Is Dependent Choice equivalent to the statement that every PID is factorial?" links to "Factorial Rings and The Axiom of Choice". (Both questions would probably also benefit from some improvements to tags - but it seems that MO community strongly dislikes bumping old questions.)

linked-questions The answer "Can we color Z^+ with n colors such that a, 2a, …, na all have different colors for all a?" links to the question "Fifth powers modulo a prime".