Ask HN: How to get contracts signed.

I'm making contracts for professional services work such as analytics consulting. What's the easiest way to get a document signed by both parties?

Enterprises are still doing the print, sign, fax thing and some like comcast are using clunky web tools. There must be a better way!

I see a few apps in the appstore that allow you to sign on iPhone. I was also wondering if something like "I agree to this contract" in an email would suffice.

Wondering if anyone has a good app or process recommendations?