E-mail signature is handy and became a business e-mail standard. MS Outlook provides e-mail signature feature since long ago. It allows you to edit it using its built-in editor or whichever editor you perfer to use. For me, I like to remove the MS specified HTML junk and therefore I've to use external editor such as Notepad.
MS has remove the right-click editing function in Outlook 2007, and the location of signature files is changed (from Outlook 2003). Here's the new default location in Outlook 2007:
profile location = C:\Users\username
In version 2007, Outlook added a nice Name card feature. I decided to wait a little bit, until most people stop reading plain-text for e-mails.