TinEye

This nifty little "thing" (image search engine) - will search an image for you by
using sophisticated pattern recognition algorithms to find your image on the web without the use of metadata or watermarks.

TinEye instantly analyzes your query image to create a compact digital signature or ‘fingerprint’ for it. TinEye searches for your image on the web by comparing its fingerprint to the fingerprint of every single other image in the TinEye search index.

At the moment, according to the website, their database contains 701,666,310 images from the web but this figure is increasing regularly!

In private beta at the moment, I can only see this getting better as time goes on and their image base increases.

I have searched a couple of my most popular images and have found no matches, (thankfully I suppose)but have been having fun with their "cool search" function!

If you'd like to try it out for yourself, as of 18th August, it's now in open beta so click on the blog header TinEye above and be taken right there!

PS. They have a nifty FF plugin too - means you can just right click and search from your image page!!