STRAIGHTEN THAT IMAGE QUICKER
So you may remember you can use the ruler to establish a baseline for the horizon of an image. Then you would use the Arbitrary rotation to straighten. Well since this became such common practice they simply added a straighten button in the options bar. Simply use the ruler to set the baseline as usual then just click on the Straighten button. Done!
This was worth the price of the CS5 upgrade in and of itself!