it took me less than a minute to get it up and running on my site.
i've never been crazy about the behavior of opening images on websites. either it takes you away from the page you were on and forces you to hit the back button, or it opens up an additional window which is plain rude.
i was using the lightbox js on my website, but i was never satisfied about the default functionality. it had a cool feature for viewing sequences of images, but i felt the effect was too severe for one at a time viewing. i'm sure it's possible to alter the lightbox script to suit different needs, but that's outside my code monkey abilities.
anyway i like FancyZoom. it's from Cabel Sasser of Panic software. (if you're using a mac and maintaining a website, i highly recommend you give Coda a try. what little coding i am capable of i taught myself using Coda.) FZ is free to use for non commercial websites. if you make money off your site (i sure as hell don't) it's a one time fee of 39 bones. though i'll gladly fork over the money if things get rolling over at inksktink.net. ha.
apparently FancyZoom has issues in IE 6 (because IE 6 is terrible), but for reals... nobody worth knowing uses IE 6 anymore.