While it isn't an every day occurrence when a TD needs something officially signed. However, in freelance situations, it would be nice to have. There have been a few times when I would have used this technology in the past for small freelance TD jobs.
There are a couple options out there that will help you get those signatures. once company is Docusign, and the other is Echo Sign.
Of the two, I have only personally used EchoSign. It was easy to use, economical, and saves your documents (amount depends on your pricing plan). I used it for sign rental contracts and the rental agreement, but it could be used for a variety of contracts.