View SSL/TLS certificate in Safari 5+ when no padlock icon shown According to Apple,


  With Safari 5 through 5.1.7, a lock icon appears near the top right
  corner [only] if all of the webpage's content uses a secure connection.


That's all very well, but normally to view the SSL/TLS certificate for a webpage serving content over HTTPS, one would click the padlock icon.

Because the icon is not present on pages that serve only some of their content over SSL/TLS, there ought to be another way to view the certificate, but what is it?
Recent versions of Safari do not appear to display the lock icon or certificate unless all content loaded by the page is https. For example, if the page URL is https but it loads a JavaScript file via http, no lock icon. 

The only workaround I've found so far is to run the openssl command in Terminal, like this:

echo ^d | openssl s_client -connect host.example.com:443


This will show you the certificate chain back to whatever root authority is used to sign, if any. "verify error" will show things like "self signed certificate".