We've been working on a much of re-branding here at the company I work for and one of the tasks was getting everyone updated e-mail signatures. So I hacked together this simple generator based on ext.
It's pretty straight forward to use. Enter your info and click generate.
The signature format is handled by a template which can be tweaked to your hearts content. Check out the sigTemplate in sigGenerator.js again it's pretty straight forward.
The download feature requires it to be hosted on a webserver and uses a little fileEcho.php script. Please note that is would be a VERY VERY bad idea to host that on a public server .. you've be warned.