The iFrame Tag
I have mixed feelings about the use of <iframe>.
Whenever I have seen it used in the past more often than not it appeared to be somewhat a "shortcut" on the part of the web developer. This and the use of an iframe technique to forward an un-populated domain name.
W3C suggests the use of an iframe to include YouTube videos on your webpages.
Mozilla say:
I also have a discussion page on the <FRAME>, although this is not supported in HTML5
Frameset Forwarding
This is often offered by a Domain Registrar for free if you don't subscribe to a hosting package.