This works quite well with an Iframe, I've used it a lot. One one site I have used Iframes for: a page that are links to photo albums (the albums were already made by someone else with hundreds of photos so it was easier to use an Iframe to display those albums than rebuild each one), a mapquest page, page that is a pdf of a membership form, page that is a pdf of a newsletter, page that is an embedded google calendar. There's probably more, but the idea is that the viewer never leaves the actual original site. All the site navigation is still there so they can still go to all the regular pages when needed.

Jim