Eric just released a phenomenal bit of javascript called FrogJS. Basically it allows you to do paging between your pictures in a lightbox-type gallery.
This is a pretty neat little script. My only qualm with it is that it’s currently 760px wide. It’s not exactly going to work within your standard website template. I think the point of the typical lightbox is that you can throw your images into a template where your content area is typically 500 px in width, and the image pops up with an AJAX-y effect of muting out the rest of the screen.
Perhaps this concept can be taken further in this regard! I will definitely be playing with this.