Trueshot Aura is my current favorite 31 point talent available to Hunters. It's in the Markmanship tree. At level 60 this increases the attack power of the entire party the Hunter is grouped with by 100, as long as the party members stay within 45 yards of the Hunter.
More attack power means more base damage on the Hunter's Aimed Shots, Multishots, and Autoshots. (Attack power doesn't modify Arcane Shot or Serpent Sting.) This feeds into larger critical strikes too.
Trueshot Aura has the benefit of being a passive ability. Once you flip it on, you don't have to worry about it. It's just there, doing its damage-enhancing goodness all the time.