point well taken, since users can enter and edit the database of companies, how would you approach trying to keep some semblance of security for the database without knowing who is modifying it?

Anyone can see it, log in to write to it.

thats how it works. Then to see matched companies, an email is all that is required for registration to be able to create a profile (past and current employers) and then have Genotrope create a graph of related companies which show up on the find page.

Try to get past needing to create a profile. Let the user enter as much data as necessary and save it in the session. If they like what they see they can decide to create a profile.