1. when you're first contacted by a recruiter, company provides a written set of values/principles that the company expects from its recruiters and staff, contact info if you feel the company didn't live up to these principles, or have a suggestion for how to improve the process.
2. tie x% of recruiter comp to good behavior, and y% of interviewers.
3. automatically send surveys to candidates (both accepted and rejected) and check to see if you feel they could've streamlined the process or made it more pleasant. Capture an NPS score. Offer a cash bonus thank-you and another for referring friends.
other ideas?