There is a modified version of the Adds Images as planes add-on that lets you stack series of images on a determined axis and determine the offset.

![enter image description here][1]

![enter image description here][2]

The script can be found [HERE][3]

The full thread on [blenderartists.org][4]

**NOTE:** Keep in mind that is a modified version of the original script so you might need to move the original out of the scripts folder so that blender doesn't complaint of having multiple addons with the same name. 


  [1]: https://i.sstatic.net/tHWTx.jpg
  [2]: https://i.sstatic.net/sgq83.png
  [3]: http://blenderartists.org/forum/attachment.php?attachmentid=305639&d=1398650875
  [4]: http://blenderartists.org/forum/showthread.php?333722-Import-images-as-planes-addon-for-Z-axis&highlight=stack%20images%20as%20planes