I can't help but think that browser vendors could have at least made an effort to make client certs and Kerberos authentication more user-friendly on the web. Perhaps not so useful for private consumers, but it would sure come in handy in enterprise.
Is there a good place to go for the current state of client certificates?
I've heard that there was an issue where other websites could see the certificate, so there were privacy problems with having them installed.
It seems like something that would have been fixed, but it's hard to search for. Server certificates are so much more common. They end up taking over all the search results.