Yesterday I received an email that opened with "I recently came across  your resume on the internet and believe the job opportunity below would  be of interest to you." I get an email like this every couple of weeks. I  find this interesting for two reasons. One, my resume has not been  active on any sites (Dice/Monster) for over 4 years, and two, you think I  am interested because of a single keyword in your search.
This brings up a good question. 
What do I look for in a Recruiter?  Over the past several years I've worked with many different recruiters  in the Twin Cities, either when I've been looking for a new  contract/position, or been in roles where I needed to hire contract  resources. Like any profession, there have been some really good ones,  where I keep them in my network and continue to reach out to them when I  have a need, and there are others, that, well, let's just say I no  longer have their business card on file.
Here are four keys that I view as to what makes a good recruiter:
1. Have a relationship with the hiring manager and/or client company. It's  easy to just glean open reqs off of vendor management systems, and  throw a bunch of resumes at them, hoping that one of your candidates  will get selected. Having a relationship is going to give you a true  understanding of what the client is looking for and what you should be  looking for in a candidate, which should give you an edge over other  recruiters.
2. Know what the position is that you are recruiting to fill.  When you get a req, don't just read the description. I can do that. Too  many position descriptions are boilerplate, and may not always reflect  the client's true need. Work with the client to find out what is behind  the req. (Relationship) What is the real scope of the work? Are they  posting for a Technical Program Manager when what they really need is a  Business Analyst or Developer? Knowing what the client is looking for is  only going to enable you to find the right candidate and sell that  candidate on the position.
3. Get to know me. My best experience came from a former recruiter who has become a good friend - 
Robert Stanke.  (Ok, it's Bob to most of you, but I met him when he was still Robert!)  When Bob first recruited me, he was working on a couple of open reqs  that my experience matched up with pretty well. Before Bob would submit  me as a candidate he had one requirement - we had to meet for a 1:1. He  wanted to get to know me so that he knew what I was looking for in my  next position, what I liked, didn't like, what made me tick, the things  that don't come through on the resume. He wanted to get to know me so  that he knew how to present me, and could sell me to the client.
4. Communicate.  Keep me in the  loop.  Once I’ve been submitted, a periodic update would be nice to let  me know the status of the req.  Has the req been filled or closed?  Delayed? Am I still in play? I’m working with a recruiter now who  provides me a weekly status update on an open req she’s working.  I know  things come up in a business and positions are delayed and canceled.   With a good client relationship you should be aware of what is going on  with the req and be able to communicate the status to the candidate.
These are the four keys that keep a recruiter in my network and their business card in my file.