When I needed to recover RAW image files from a Compact Flash card that my Nikon D70S showed in the camera but were not visible through the card reader I tried a few apps. PhotoRescue is the only one that worked and it was fast and simple to use.
Exif Untrasher could not find the images. FAIL.
CardRaider took several hours of preparation then crashed. FAIL.
FileSalvage couldn't find anything. FAIL.

PhotoRescue allows you to see if it can locate the missing files in demo mode before paying for the app. Once the items are located you sign up and when the registration code arrives you can then save the recovered files.
US$30 is a fair price for something that works so well and does what the other apps mentioned above could not.

I don't normally write reviews for apps but as finding this one was such a task I figured this might help others in the same situation.