If you go to the themes gallery here, you can click on the theme to go to the theme page, then when you click the preview screenshot, it loads the example theme in a lightbox. I like this much better than pop-up windows, but can't find a way to easily do it in WordPress. WP also uses this in the admin control panel when you are looking at plugins.
Is there a plugin that will allow you to easily lightbox another webpage or other content? All the Lightbox plugins I could find were designed around lightboxing images. They're cool and I like them a lot, but would really like to be able to do some content, like WP and WordPress.org do. Can anyone point me in the right direction?