Drawloop converts pretty much any kind of file you throw at it into a PDF. It also can combine multiple files into a single, multi-page PDF, and -- here's the best part -- offers a free esign service as well. When you use esign, Drawloop sends your recipient an invitation to display the PDF in a browser window and adopt an electronic signature which they can drag into the document.
You don't even have to log into Drawloop to use most of the goodies, though a free account is required to use some of the more advanced features (like rearranging pages in a PDF). Amazingly, you can make multi-document PDFs and electronically sign them all without an account. Drawloop has become my favorite way to seal the deal on simple contracts and freelance agreements.