The agency at which I work holds the Yahoo! Europe account, and I occasionally work on it. Most of the stuff I do for them is for internal use and so confidential, but I did help them make this banner for their new enhanced mail service.
The idea was that you are invited to take part in the beta trial of the new product, which is so fantastic that Yahoo! can't keep it a secret any longer.
I know, I know...
This is a Flash file, by the way. So open it in your browser.