data: is the new “Bookmarklet”
A data: URL directly contains its content; for example, data:text/plain,Hello%20World!. The main usefulness of this is that you can do things like including images inline in a document. But you can also use it to create 'anonymous' HTML documents, where any link to them or bookmark contains the entire document.
I originally did this in 2006 when I was in need of a URL-encoding tool and did not have one to hand; so I wrote out:
data:text/html,