General photo gallery efficiency questions

For some reason all the flash work I’ve been getting has been photo galleries, so I think I’ve worked out a pretty good model for creating one. However I haven’t spent much time testing out different methods so I’m not actually sure at all what I do is developed well… Anyway I was wondering what kind of class structure/model people use to create their image galleries.

Also, a question I haven’t really bothered spending much time on but always wondered: assuming individual pages are made of a list/grid of thumbnails of the images; once a visitor leaves a page is it best to delete it and let it be garbage collected (thus saving memory)? Or is it best to keep all the old pages recorded in an array or something so that it does not have to be recreated if you return to the same page?