I recently had an idea to make HTTPS more secure for the average user: What if Google were to check the certificates when crawling a site, ensuring that its keys did not change in a malicious way.

Now, sites could present a different cert to Google IPs and to users. To solve this problem, the html anchor element could be augmented with the certificates fingerprint. The users browser would make note of the fingerprint and alert the user if something is off.

I think embedding information about a certs finger print or its root CA in links makes a lot of sense, as it would allow a sort of "web of trust" between linked sites.