Paul, 

That is a great answer by Leonid.

We take things a step further by adding custom "blocks" on all pages of the site. These blocks are RAW html, with instructions on what to do next and only visible to Unconfirmed.  

We then customize all other blocks and menus to be visible based on the level we set, some people can see things, but not interact with them. Some sections of the site are completely invisible and only available via invitation.