ability to arrange stuff with equal spacing based on actual space and not the center.
ability to bring the back handle bar to default as you can do with front handle bar when you have pen tool selected and hold alt key.
ability to bring back handle bar of either one side only to default as you can when you hold alt and has direct selection tool selected.
ability to arrange paths in order of front and back on the same layer.
ability to merge vector masks easily, dragging replaces it..i wish holding key could make it switch between replace/add/subtract/duplicate.
Illustrator brushes- stretching symbol etc.
Illustrator stroke management.
spray symbols with variability- so i select 5 different flowers and make brush out of it so when i draw it draws randomly between one of 5 flowers with varying scale and any other factors that i have enabled.
ability to mask a group or apply filters to a whole or clipping mask. and more but i cant recall now.
edited: Handle bars are that come out of anchor points that you drag around to determine how curved the curve is... edited: I have CS 5.1