Just been round to a friends and he's got a new Photoshop plugin that looks pretty neat. I didn't get that much a chance to play around with it but from what I did see was pretty impressive
http://www.athentech.com/why-perfectly-clearIt can work on sharpness, color, focus and a lot of other things too and while $120 isn't "cheap" it does seem quite good value.
I have nothing to do with this company BTW and haven't been offered anything for making this post...
...excuse me a minute while I open this cheque from a company that isn't Athentech....