When you delete files from your PC, you don't really wipe them away forever. The system simply marks that space as reusable, which means that erased files can be actually be recovered with apps like PC Tools File Recover.
This program features three different modes (Quick, Deep and Physical) to scan your computer in search of previously erased files. I specially liked the possibility to filter this scan, either by file type, file size or even specifying letters or words that must be found in the file's name.
Of course, the most thorough the scanning method you choose, the longer it will take to be completed. On the upside, a Deep scan shows far more results than the Quick one and the Physical scan can be useful in case of corrupt hard drives.
However, I was disappointed to see that this trial version doesn't allow you to recover any files. It scans your PC and displays the list of all erased files, but if you want to recover any of them you'll need to register the program. I understand this is a shareware version, but I think users would like to have some kind of guarantee that they'll be able to recover their data. And maybe a good way to do so would be to have a fully functional version for a limited period of time, or at least allow users to recover a few files before registering the program.