The Lightbox 2 plugin uses JavaScript rather than Flash, but I think it will be just what you’re looking for. If you want to use it with the built-in WordPress gallery, install Cleaner Gallery as well. The when you write a post, upload your images to that post and press the button to insert the gallery into the post.
Here’s what it looks like on my site if you want to take a look (click the images, obviously).
Thanks, but I was more focusing my attention on something like MyFlash (http://alexrabe.boelinger.com/wordpress-plugins/myflash/), though it requires MyGallery, which I do not seem to be able to use: I install the plugin, then I cannot find how to edit its preferences.
