Many HR departments are too lazy to look through resumes submitted directly and use their tried and true headhunters, so they shouldn't be completely discounted. I've had good and bad experiences with headhunters although none have actually gotten me a job (one got paid for it though). My successful applications were...
1. Alumnus contacted school for resumes and found me.
2. Brother in law of former co-worker/ friend at job 1.
3. Direct application to company in response add.
4. Referrals from two former co-workers/ friends from job 1.
With my current job I had a headhunter put me up f/ a job interview in a different department, which turned out exactly what I told him I wasn't interested in. When I told the headhunter I wasn't interested in that job he seemed pissed and never called me back. That is until I did get a job in another department based on recommendations from friends and my own networking. He didn't help with negotiating or anything, but when my future boss found I had interviewed before through a headhunter he had to notify HR. They paid him a commission to maintain their relationship. I understand that, but I was pissed at the recruiter because the way he treated me and the fact that he got paid in the end for virtually no work.