A friend sent me an e-mail asking if I had heard about a piece of software called Anagram. I hadn't so I checked out the site.
Check out the screenshots under "How it Works" to see exactly, well, how it works. I downloaded a copy and tried it out and it works exactly as advertised -- signatures on e-mails are automatically populated directly into Outlook contacts. For people that send me e-mails and are not using Plaxo, this is a massive time savings for me as I no longer have to copy and paste the information from their signature into Outlook contacts.
I haven't yet tried it to populate an appointment, but there are plenty of people around the office that haven't figured out how to send Outlook meeting requests, so I'm sure that I'll get to test that functionality shortly.