I love Lightroom. But it seems that Adobe created some really cool features for it, and then hid them.
One of those tools is the Targeted Adjustment tool - aka the magic button. The targeted adjustment tool looks like a target, and can be found it the upper left of the tone curve or HSL sections.
(the targeted adjustment tool is the little target right under the H of hue. Just click on it to activate it.)
So what's it good for?
Well lets say that you have a really great landscape photo but the side of the mountain is a bit dark. Just grab the magic button in the tone curve section, take it to your too dark mountian, click right on the dark part of the mountain, and drag up. The tool will target that specific region on the tone curve and lift it without affecting lighter or darker areas. It targets the adjustment.
I seem to get a lot of oranges that look too saturated. Outside it's great, everything looks beautiful and vibrant. But inside, especially where there is furniture showing I get some very saturated oranges/reds. If I want to desat a little, instead of having to try to determine the perfect blend of oranges/yellows/reds, I just grab the magic button, click on the offending section of the image, and drag down a little. Lightroom figures out the perfect blend for me.
Or if I've got a sky that I want to bring out. I'll use the tool to grab a little blue and drag up to increase saturation a little, and drag down while in the luminance tab to darken my blues just a little. Everything else will be left alone.
You do have to be aware, though, as you use the targeted adjustment tool it will adjust everything in the image with the same color/tone.