I thought I'd write a quick note to highlight a feature of Aperture that I find so useful and powerful and that isn't called out (at least past the use under "quick brushes") in the material out there on Aperture that I've come across to date. This is the ability add new blocks of the same type of adjustments. What do I mean by that? Simply put, you can make one set of adjustments - be it with sliders or brushing in or away an adjustment in one area, and then add that same adjustment again with it's own set of commands. Now, this is actually really evident within adjustments like the brushes - a dodge adjustment for the eyes of one subject and another to lighten the teeth perhaps on another. But take a moment to look at the the little gear icon in the upper right hand corner of the adjustment boxes for things like the color set (hue, saturation, luminance, range). You'll see there than you can not only move the sliders, but also brush in / out a location specific color adjustment. So you've used a slider to bring down the luminance of a blue color cast that was making some blonde hair alien-like in that outdoor portrait, but you want to go back and add in some blue locally on your subject. You can click the little gear icon and select: "Add New Color Adjustment" and a whole new set of hue, saturation, luminance, and range adjustment sliders (along with the brush in/away option) is added - and it's independent of your first color adjustments. In this way, you can make global and then local adjustments, adding in however many you may need. You'll see this option under the various adjustment gear icons - e.g. under the highlights and shadows adjustments, you can create multiple adjustments to brush in shadow reduction (fill light) or bring highlights down / work globally and then locally; the same for levels, etc.