Headhunters, Employment Agencies and Third Party Recruiters are all valid options for college grads who are looking for new careers.
CollegeGrad.com has a list of questions you could ask a Headhunter, Recruiter or Placement Service working on your behalf.
Using a Placement Service
Questions College Students Can Ask Headhunters
Headhunter Can Open Door You Can't Get Through
Working Well With Executive Recruiters