The concept of digital signatures is one of those things that many people get excited about, yet dismayed very quickly when attempting to implement a solution. Digital Signatures remove one of the last remaining needs for paper, the need to sign documents. Adobe is aiming to cut through some of these digital signature challenges by offering a hosted eSignature solution.
How does it work? Simply sign in to https://esign.adobe.com, upload a document and type in the email address of the recipient. That person will receive an email with a link to the document you sent. The recipient then agrees to sign the document. Finally you recieve an email informing you that the document has been signed. Easy!
Once signed, you can download a copy of the PDF, certified by Adobe complete with timestamps of when the document was signed by you and the recipient. If anyone tampers with the document the signature will break, thus ensuring the integrity of the file.
Adobe eSignatures is currently in beta, and while it will work worldwide, the signatures are only legal and valid in the US at this time. I still recommend you check it out and provide feedback!