Monks at the oldest Christian monastery in the world - St. Catherine's Monastery on Mount Sinai in Egypt - plan to use digital cameras to extract hidden information from ancient Bibles. Using hyperspectral imaging, which takes pictures of the pages at different wavelengths, the monks will attempt to extract hidden text from the 1,600-year old Greek Codex Sinaiticus, the oldest existing Christian Bible. The monks hope to be able to use this method to retrieve faded revisions that were made to the parchments by hand over the years by ancient scholars.
You can read more about this on the Reuters News web site.
I wonder if the same technique can be used on some of the newer but still unreadable documents that genealogists sometimes encounter. In any case, it sure beats trying to do it with lemon juice and blow dryers.