There are modules available that do this.
On the commercial side, I've used Mandeeps' Live Content module a lot. I like it! I believe that ZLDNN also has a similar module.
Also ...
http://www.dotnetnuke.com/Resources...posts.aspx shows how to use lightbox effects with Ventrian's News Articles module. I expect that the techniques can be extended to other modules.
Here is another one:
http://dnnuke.blogspot.com/2007/12/...image.html Pretty much anything that you can do with jQuery and jQueryUI can be incorporated into skins and modules.