I tried a few options, although none of the ones mentioned above, but the best I have found is Lightroom. For most images, I set the defringing to all edges, then adjust the CA sliders to match the lens/image, reviewing manually. Once i know a lens, I have a pretty good idea of where to set it. In scenes with a lot of high contrast areas, I set the defringing to highlight edges only, to prevent a grey line appearing along the transtion areas (particilarly the horizon). It isn't perfect, but it removes enough to stop it being obvious without pixel peeping (and then you have to look quite hard most of the time). I've never been able to see it in an A3 print from either the 7D or 5D MkII using this method. Mind you, the lenses I usually use with the 7D don't tend to have a large problem with fringing or CA, unlike those I tend to use on the 5D MKII.