Monkey Lunge is a feat introduced in a Pathfinder Companion, and reads as follows:
Prerequisites: Lunge, Acrobatics 1 rank.
Benefit: As a standard action, you can use the Lunge feat to increase the reach of your melee attacks by 5 feet until the end of your turn, without suffering a penalty to your AC. You cannot use this feat if you carry a medium or heavy load.
Normal: You take a -2 penalty to your AC until your next turn when making a lunge attack.
Is there ever any use for this feat?
Given that activating the ability is a standard action, you have only a move action left in your turn, which you cannot use to attack. The ability ends at the end of your turn, which means that after your move action your reach drops back again. Unless someone readied an action to charge you after you used Monkey Lunge (thus provoking during the middle of your turn - an incredibly odd readied action indeed) I do not see how you would ever be able to use this feat and make an attack with it.
What am I missing?