We need to implement a gallery feature for our client's new website. They had a similar feature on their last site, which used Smooth Gallery, which in turn was based on Moo Tools.
We could go ahead and do the same however, before we do, does anyone have any suggestions for alternatives and if so, please explain why you feel your choice is better.
The most common option is LightBox - there is a pure JavaScript version and LightBox 2, which is based on jQuery.
You'll really need to compare all of the options yourself to see which best suits your needs, but LightBox allows you to have a collection of thumbnails with back / forward navigation on the full size images and if JavaScript is turned off, it your gallery will still work.
I usually use fancybox (http://fancybox.net/) along with Scrollable (http://flowplayer.org/tools/scrollable.html). You can view my example of implementation (pretty shaky for now) here: http://events.coffeencode.org/photos/1/