View SSL/TLS certificate in Safari 5+ when no padlock icon shown
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".