Have you participated in Firefox's Download Day?, If you have you can show it off by downloading and printing your very own personalized Firefox 3 Download Day certificate.
Just head over to http://www.spreadfirefox.com/en-US/worldrecord/certificate_form and type in your name and hit submit, You will then be directed to a PDF download of your cert, You will need a PDF read to view your cert, You can get one Here

Here's mine!:

Did you get one?