Catpoints is an addon based off of Toskk's cat DPS calculator. It adds a value to item mouseovers which shows the dps upgrade/downgrade of equipping it. Unfortunately it hasn't been updated in 2 months on the source I use to get it (Curse addon updater) and I can't seem to track down an official site. Does anyone know if there's a version out for how things should currently be weighted, or another addon that does the same thing?
I've had Pawn suggested, but what I really liked about Catdps was that it automatically adjusted to my current stats, compensating for what I was losing.