Macrium, aside from full drive images also has options for File and Folder backups. But I just checked and the latter function is not available on the free version (which Martiin wants), so I guess this rules out this program. Sorry.
Huracan- With either TrueImage or Macrium the imaging of either the entire drive or a given folder will result in an image file that can be mounted as a virtual drive and manipulated in any file manager. So the extraction of any individual file is simply done.