Pro tip: Email signatures are simply no longer needed after the first correspondance with someone. People can tell who an email is from without any need for a signature.
Yes, this goes for short signatures too. Like "Thanks, Name". It simply isn't needed. Also, it makes threads in Mail.app and Gmail clients look so much cleaner without any signatures.
So, keep a copy/pastable signature around (or you can use the Canned Responses Lab feature in Gmail) that you can use for the first time you email someone. After that, ditch it.