Someone (Waddo I think) was attempting to make one for a game, but depending on how complex the captcha you want to decrypt is determines whether or not it is possible. A screenshot of one would be nice for us to help you (also, it is generally frowned upon to bump topics after only a few hours - normally 1day+ when there are a lot of other topics above it, otherwise preferably never).
By reading this signature you agree that mixster is superior to you in each and every way except the bad ways but including the really bad ways.