Stumbled across this topic many times in the last years, but anybody from the forum tried photoshop/GIMP to make some nice see through photos?
For those who have never heard about this X-Ray technique... here is one tutorial.. just try it out yourself and play a little bit with the filter settings
Tutorial: http://imgur.com/XNWJo
And a detailed explanation how to set up the infrared filter for X-Ray: https://blog.udemy.com/x-ray-photoshop/
Should also work with GIMP, but I think Photoshop has better results.
And Photoshop (CS 2 or higher - this technique should work after PS 6.01 and before CS3) you can download for free on the Adobe website (Adobe Photoshop CS2). Together with the serial number!
Tipps and hints are welcome.. also some examples