The suitably-titled Show Document is a web-hosted service that serves one specific aim: enabling you to launch a document sharing session on the web at any given time. That is, you upload your document and invite your friends to see it along with you, and make as many suggestions as they deem suitable.
The Show Document webpage is subdivided accordingly, as one half of the page is aimed at those who wish to begin a session of their own, whilst the right-hand side of the main page will enable anybody to join a session that has already started.
In both cases, the process is completely hassle-free. To begin a session, all you have to do is select a file to be uploaded, and once this has been dealt with you can launch a live session. On the other hand, if you wish to take part of a session you have been invited to you simply key in the code of that session and then you will join in the discussion immediately.