As promised, I'm making a list of alternatives to the standard Lightbox. (
http://www.huddletogether.com/projects/lightbox2/)
Well, I haven't tried them all, but it's usually the same with them all.
Include 1-2 Javascript documents and a CSS.
#1 - Lightview:
http://www.nickstakenburg.com/projects/lightview/
One i recently found, and I think it's pretty new. Looks good, and got the forward/previous arrows on the outside, so it won't get in the way of the images, which is a nice feature. (He's also working on a version 2, which will be able to play youtube videos and more)
#2 - Jquery Lightbox:
http://www.balupton.com/sandbox/jquery_lightbox/
This is a pretty simple, fast and nice-looking one, as well. Looks a bit like Lightview, just with a smaller frame, faster loading and a little roll-over effect on the description text.
#3 - Multibox:
http://www.phatfusion.net/multibox/
This one is pretty new to me, as well. Looks good, some nice transitions and with a different look that you may know from Lightbox. This one also shows almost all you could ask for. Iframes, html sites, mp3's, flash, wmv etc.
#4 - Lytebox:
http://www.dolem.com/lytebox/
This gallery got rid of the framework requirements, such as Mootools, scriptaculous, YUI, Prototype and so on. It also comes with a slideshow-feature, but looks like Lightbox.
A little quick list with some alternatives. I may have missed some other good ones, but my bookmarks are a mess atm, so this is what I could find for now. If you know some too, feel free to share them with us :)
Also remember that it's easy to customize these galleries. From colors and transition-time to editing the different buttons (next/previous/close). The javascript files that comes with the galleries is usually more obvious and easy to edit, that you may think. You can do it with some very basic javascript-knowledge.
If you got any question, don't hold back. Hope there's something you can use, enjoy :)