I too have been on the receiving side of resumes and I have to agree with the statistics that the average resume gets read for about 6 seconds! General appearance and brevity is what gets it read longer along with relativity to the position. Cover letters are a nice professional touch and should be a brief overview of who you are, what your expertise is, and what your aspirations are. The resume proper should be more specific information on what your cover letter said about you without being waaaaaay too detailed. Somewhere either on the cover letter or resume should be the disclaimer that further information is available on request, which can also be an invitation to an interview.
Once the resume makes it past the initial 6 seconds if the candidate seems interesting then it gets read a little longer and perhaps in to the 2nd round pile...