Remove the haze
So one thing I recently found on the awesome Phase One Blog is how to remove haze from a photograph. If you take a landscape picture and expose it as usual you often end with blank spaces on both sides of your curve (visible in the Level display).
Lets take this picture I took from Osanbashi in Yokohama:

Canon 5D MkII and Canon EF 50/f1.2L @f4
It is darker because I underexposed it at -1/3EV to have more data in the dark area, which is easier to recover and there is a lot of haze because that day was quite cloudy and humid anyway. Furthermore the colors are all very mushy and the brown of the sea is not really visible. But not fear, this is all fixable.
Before you do any adjustments on the levels, all other things have to set into place. Fixing expores, brightness, highlight and shadow recovery, contrast and saturation, etc.

I increased the overall brightness a bit, added some shadow recovery (for the dark areas in the pictures) and added some clarity because this is a landscape shot. After this changes the picture already looks much better:

It comes to a point where it is much usable, but we can do better.
So in the final step we crop away all the unused parts in the three levels for red, green and blue:

Gone with all the not needed data.
After this change the result will look like this:

If all the levels are adjusted correctly the picture will not have any strong color casts. If there are any strong off casts the right side of of level for this color has to be adjusted and any other to get a good neutral color hast. Optional and better is to shoot with a color/white balance card and adjust at this level.
When both pictures are compared, it is very easy to see what you can do with this tool.
Here are two more examples shot from the Tokyo Government building and in the area around there from the Sanpo Japan Tower.

Left is before (unaltered, thats why it is not straight), right is the final edit.

It is clear how easy it is to get some more punch out of some dull pictures. Furthermore it is another reason why the only way to shoot is shooting with RAW.