http://www.collegegrad.com/coverletters/

I read the advice on this website pertaining to cover letters and what I gathered from it was that the most important thing was to make the cover letter unique for the specific job you are applying for. I entirely agree with this and understand how annoying it is to get something that has obviously been sent to a whole bunch of different people, and just been personalized by inserting your name into the space. I imagine reading a resume/cover letter that has been mass mailed like this, is somewhat like when i get junk mail and it says something like dear loyal customer. I imagine that they would do the same thing with the resume that I do with the junk mail, that is throw it in the trash without even reading the rest.