loupe.js 2.0 allows you to add photorealistic loupes (magnifier) to images on your webpages. The design is changeable by use of an image editing program. It uses unobtrusive javascript to keep your code clean.

It works in all the major browsers - Mozilla Firefox 1.5+, Opera 9+, Safari, Chrome and IE6+. On older browsers, it'll degrade and your visitors won't notice a thing.