====== DocuSign ======
From: https://www.docusign.com/
Sign documents anywhere from any device
A couple of taps on your iphone or iPad and you’re done.
More secure than paper
Documents are encrypted and a complete audit trail is maintained.
Document cannot be changed and resides in the Cloud.
====== CudaSign ======
From: https://www.cudasign.com/features
Looks similar to docusign
====== Electronically sign a PDF ======
From: http://www.howtogeek.com/164668/how-to-electronically-sign-documents-without-printing-and-scanning-them/
Instead of digital signatures, we’ll be using electronic signatures. They are just like
traditional ink signatures, but applied electronically to documents without any printing or scanning required.