Many of us use levels--you know, adjust the sliders 'til it looks better, opening up the shadows or throwing black to real black. Maybe make white a bit brighter. But if you're working with only the composite RGB channel, and not playing with the discreet channels separately, you're missing a level of control that can really save a picture.
As seen above, the colors weren't really true in the top image. There's a yellow cast over the whole image, and that cast is getting in the way of the proper "pop" I was looking for.
So just for kicks, I started playing with each color channel separately. (Hint: Do this as a separate levels adjustment layer, rather than making the change in your base layer.)
Using each of the RGB channels separately allows you to maximize the dynamic range of each color, and get absolute control over the color output.
Tell me, doesn't the bottom version look a lot better?
Oh, the thirty seconds is up. BTW, if you're a real control freak, you'll control your color channels in Curves, since curves give you much more control than levels. But that's a story for another day.
Let me know if you find this info helpful, or would like additonal info.
Thanks,

Eric