There’s another great jQuery lightbox plugin making its rounds at the moment, and this one’s a doozy it would seem! FancyBox is a well-coded, nifty little image lightbox jQuery-driven script that can be used to either display images, html content or even multi-media in a Mac-style “lightbox” that floats over the currently displayed web page.
Features include a nice drop shadow under the zoomed item, the ability to group items together by adding navigation (aided by preloading of images) and the ability to display the lightboxed content either inline, with ajax or in an iframe. Of course its display can be extended and customised through various settings and CSS and it does support some fancy transitions thanks to its use of the easing plugin.
And yes, just in case you are wondering, there is a WordPress plugin available for it! :)
Related link: http://fancybox.net/home