This comes close enough to my Auto Zoom Icons script that I tried to take down his server. But since I wasn’t able to — because I’m a lousy h4cker — I thought I’d just post the link instead…for now… 
Dynamic thumbnails and preview images with DOM, CSS and PHP
you can see small camera icons next to each of the links in the following list. Activate these either via mouse or keyboard to see a preview of the linked image