Good tools for building a call for proposals in Civi?
Zak,  I agree with Peter's comment. If you are using Drupal, you can use the CiviCRM Drupal webforms integrations.  There were a few good examples of these at the CiviCRM User summit last week  (i.e - Susan's ReThink Church example - which is essentially what you want).  

Basic concept: User logs in and starts to fill out a multi page webform that saves the data on their CiviCRM record.  If you want to add a little custom code, you can have the final page be a "signature page" so that it can not be edited again.