Broker Brain allows you to create multiple Email Signatures. You can have one signature you use as your default, and you can create others to use for different receipients. But here's a tip on getting the most out of this feature:
Use Email Signatures to create templates for emails you send repetitively.
If there are paragraphs you find yourself typing in over and over again or cutting and pasting from somewhere else, create an email signature, name it appropriately, and type the repetitive information in the body of the email, as shown below (for information on how to create an Email Signature, click here).