This opens a lot of possibilities, but what I really like about it is that you can easily extract images or other embedded documents out of Word, Excel or PowerPoint files.
Better yet, this (finally!) gives me an easy way to find out why a PowerPoint presentation has a huge file size, even though I used "Compress Pictures..." before I saved.
I could put this into practice today: a colleague asked for my help because he had a PowerPoint presentation with about 30 slides, some of which contained pictures, and the file size was 11MB. Too large to send as an e-mail attachment in our organization.
I first looked at the obvious things: no master slides that were not used, no pictures that were scaled down to 25% or less, all pictures compressed and cropped... nothing that would explain the 11MB.
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I could not have seen that in PowerPoint 2003: the images themselves were less than 300x300 pixels and were scaled at 100%, so everything looked OK.
After replacing the pictures with a .jpg-version, the PowerPoint presentation shrank to a mere 3 MB!