http://chcheck.com You can create checklists, create and track changes between instances, diff changes between the master and instances, create iterative checklists, embed checklists in other checklists and set dependencies. Also the interface was built with usability and flexibility in mind. I have also added task, data list, comment, contact and document management since all of those are necessary for a good proces…
The public workflow would need to be super-simple looking (that whole web 2.0-ish look 'n feel) with prominent search. Perhaps something like: chcheck.com/business vs chcheck.com/public and chcheck.com/ would represent the user's path choice.
Just some thoughts - perhaps you're already moving down a similar path. Best of luck!