Searching pictures

I came across this interesting little website the other day: Retrievr. It's an experimental webservice that allows you to search for patterns on Flickr, by drawing a rough sketch of what you're looking for. The search is based on an algorithm that will only match larger shapes so don't expect to get exactly what you draw, unless you draw a really simple shape (like a vertical line or something simpler ;-) But the poor results are probably due to the size of the database.

Xcavator offers another way to search through pictures. It's rather complex but the results are much better than Retrievr. A video explains how to use the tool.

Unfortunately both are still at a very experimental level and only have samples of pictures from Flickr.