Here are some of our fave pull up variations:

Close-grip (curl) chin up

Neutral-grip pull up

Wide grip (overhand) pull up

Wide grip (reverse) pull up

Verticals row (various grips)

Vertical Suspension row (various grips)

Negative chins (assisted up, lower unassisted)

Hop pull ups (jump from ground to pull up)

Pull up isometric (hanging in pull up position)