WatchDox is a great web application by Cofidela with which you can securely share your document with anyone. It allows you to specify certain permissions on the document to be shared like whether it can be printed, forwarded or not. Also along with the complete document usage tracking it allows you to add a document expiry date which decides how long the document will be usable by the recipient.
Sharing the document with WatchDox is quite easy, just go to WatchDox.com and validate your account first, then enter the recepients email address and yours too. Attach the document, set your desired permissions and send it.
Note: Maximum file size that can be attatched is 15MB and you can upload two files at a time. Supported file types are doc, docx, ppt, pptx, pps, xls, xlsx, odp, odt, ods, txt, rtf, pdf.