This picture from my 1990 trip to Japan had a large horizontal discolored streak right through the top of the photo. However, I liked the bright red color of the temple so much that I wanted to do a color fix instead of a sepia or black and white fix.
I had to use a lot of Picasa effects but I was eventually able to make an interesting final photo with the red color heightened and the discoloration successfully minimized.
This fix involved a lot of time and a lot of Picasa fixing. The most obvious edits include boost, HDR-ish, vignette and posterize.