Here's one I learned from Antonie_K on the Canon SLR Group on Flickr.
Here's a shot with the worst case of blooming I've ever taken. Blooming is basically a problem only found in digital photography and occurs when very bright areas are adjacent to dark ones I has to do with the way the image sensor elements get 'overloaded' with too much light and basically 'bleed' onto adjacent elements. If the situation is right it can happen on almost any digital camera. This shot was taken with the Canon 85 1.2L on an MkII so it's definately not a lens quality issue.
Anyway, to rid ourselves of this nasty purple mess - Open the image in CS3 and apply a HSL layer to the image, change its mode from Master to Blue, using the color picker tool select the offending color (magenta in this case) then turn down the saturation to taste (about -80 worked for this image). Thats it! No muss, no fuss. I imagine that if there was a lot of Magenta color in other areas of the image, that this technique could effect them but it would be nothing a little Layer Mask couldn't fix.
Better description of CA and Blooming can be found here.