Ajaxy Yahoo Mail has an interface very like thick mail clients, including To and Cc field labels that double as buttons that bring up the address book. Instead of copying the thick client pattern of a static label for the Subject though, they included another button, which makes it look nice and uniform; and it works, giving you a random subject every time you click it. And that is why this post is titled as it is. I just thought it was f*cking funny, as Denis Leary would say.
Well worth trying if you haven’t played with it already btw, particularly if you still lean towards thick clients. It’s very close to Outlook, in fact I’d go so far as to say that it’s probably better. Yahoo’s UI guys are very good.