TagMyDoc is one web service that does exactly this. It embeds QR code onto your documents. During a keynote presentation, meeting, discussion or video conference, your friends/colleagues/co-workers can scan the QR code in the document and have the document downloaded to their devices instantly.
The usage is simple. You just have to visit TagMyDoc.com, upload a file and it return a QR code immediately. You don’t even have to sign up for an account to use it.

Download the file, open it and you will see the document tagged with a QR code.

If you decide to sign up for a TagMyDoc account, you will be able to track your documents and sort them into various folders. More importantly, you are able to choose the position where the QR code is embedded and add a password to protect the download.

The premium version ($2.99 per month) even allows you to tag a folder, upload multiple files at once and versioning system for your documents. If you have tons of documents that you need to share and handle every month, $2.99 is actually a great deal for all those conveniences. At this moment, the service is still in beta and it is still lacking in features. Under the Downloads section, you can see that a plugin for Microsoft Words and PowerPoint is coming so you can tag the document directly within the Office suite. Mobile application for iOS, Android and Blackberry is on the way too. One thing that I hope it can implement is the ability to sync the documents with my desktop (just like Dropbox) so I won’t have to upload the files/documents every time I make changes to it. What do you think? Does embedding a QR code on your document works for you? TagMyDoc