I'm really happy with Google Authenticator at the moment. Like SMS this falls into the "soft keyfob" category, so it's less secure than a dedicated keyfob, but

I'm really happy with Google Authenticator at the moment. Like SMS this falls into the "soft keyfob" category, so it's less secure than a dedicated keyfob, but it wins in convenience not having to lug around a separate keyfob for every service...