Great plugin, absolutely love it! One suggestion for future versions would be to automatically apply Fancybox not only to images, but also to any tag that links to an image. I'm currently just using a little snippet that looks like this:
jQuery('a[href*=".jpg"], a[href*="jpeg"], a[href*=".png"], a[href*=".gif"]').fancybox();
But it would be nice to have this feature included.