Well unbaking is a issue that is hard to do it depends on how much work you are going to put into it. Certian effects suc as pat animations to keys is rather easy but other stuff relay isnt (like deformatins) doable much at all.
Anyway no such tool exsists as it depends on the rig and you muct tell the computer what works ahow etc...
And just for theese mistake saves maya offers from v4 to maintain history for files. This hould be used in cnjunction with manual renaming!