Frames in backlinks
From edit.tf development blog. Comments are welcome via email.
A neat property resulting from the URL being the frame's data is that tools like OpenLinkProfiler allow you to find the source of teletext pages out there in the wild, on the web, which have been posted as edit.tf URLs.
Of course, you need to create your free SEOprofiler account to click any of the URLs, but the domains are listed without any account, and there must be similar but open services out there too. There's ahrefs, which gives you the first hundred if you solve a few CAPTCHAs, but let me know if you know of any better ones.