I think it's interesting to make a feature that can do something like logaster (logaster.com) do:
1) I offer a FREE design to my users (I offer a value)
2) the users sign in in my site (so I have his email to send offers and so on with an option page)
3) the users create and edit his logo;
4) the user can download a low-res image of the logo
5) I offer the Hi-res download of the logo at a cheap price (landing page with sale offer)
6) I offer the user with a sale offer for a corporate identity kit (this is only an example)..
I think a process like this con convert more users in buyers...
It's useful If the user can use Pitchprint to create an "Arttext" that I can put on over design to show other products and to stimulate the user to buy other products just automatically customized...