Void pages
Going from one website to another it ain't always obvious what the page your heading for is about and/or how it relates to the original website you just came from.
I imagine A void page would be a page that is only about the relation of website 1 and website 2. It should ideally generate content related to website 3 to, the one the visitor came from as he visited website 1.
It appears in the limbo going from one link to another and either disappears after X seconds or offers a huge button to the target website.