Jigsawr started as an SVG demonstration for the 10K Apart contest by Damian Cugley, where it is entry 269. You pick an image (either using Flickr tags or by specifying the URL yourself) and it shows you a jigsaw puzzle.
This is an HTML5 + SVG + JavaScript application.
Because it uses SVG it requires an up-to-date version of Apple Safari, Google Chrome, Opera, or Mozilla Firefox; or, on Windows Vista or 7, Microsoft Internet Explorer 9. You might be able to view it on older versions of IE using Google Chrome Frame.
Just for fun, here’s a bookmarklet you can use to create a jigsaw from any page.
Drag the above link on to your bookmark bar. Then, when you are visiting the web page of an image you fancy, click the bookmarklet to create jigsaw (it automatically chooses the largest image on the page).
Note that some sites go to some effort to discourage downloading their images, and the bookmarklet will generally be baffled by these.
If you are interested you can read about Jigsawr Design and Jigsawr Minification on my site, and read the Jigsawr source code on GitHub.