It must be getting on for 10 years since I last encountered Illustra, I remember it was on a training course relating to database-backed websites way before content management systems had become the commoditised items they are today.
It had one (at least one) stand out 'Wow' feature that I've yet to see since - the ability to search for images that look like a supplied example. If I remember correctly, it was all down to a plug-in search module called 'Imageblade'.
OK, it wasn't perfect (upload an example picture of a frog, get back lots of pictures of frogs and one picture of a Porsche 911, for instance) but it was an exceptionally useful idea.
I certainly could have done with it today. Having done some mockups a while ago for a client using low-res images I found I'd lost the reference numbers and had to spend several hours trawling various stock libraries to find them back again. How much quicker it'd have been if I could have uploaded my low res versions and said "Go find me these".
Mind you, it does serve to show just how amazing humans are at pattern recognition - eventually I spotted the image I needed in amongst 60 thumbnails on the same page, despite my having forgotten that I'd cropped and flipped my low res version.