There are a couple of BB signatures, other than your name etc., that I have seen. One is "Sent via Cingular Xpress Mail with Blackberry", another is "Sent by my Blackberry Wireless Handheld". I'm sure there are other BB signatures that you have come up with or have seen that promotes the use of a Blackberry. Please share.
I have the standard auto sig on my Gmail account, and then for work I created an autotext on my 8700 that contains the same sig as my one from Exchange, that populates when I type "*sigw" into an e-mail.