I agree that your resume should be tailored for the job. If you are applying to a large company, you definitely want to include all the buzz words for that field, since that will get yours pulled out.
But - you should do some other stuff also. I’ve seen studies that show job boards are very inefficient for getting jobs. (I can look up a cite if you wish.) You need to figure out something that distinguishes you from everyone else, find a few companies that seem to be good matches, and study them. Figure out where in the company you’d fit in, and find the name of the hiring manager for that job. See if they have job postings on their web site. Those won’t have the right name, but if you find someone who knows someone who knows someone in the company, he or she could look up the post internally and find the name and number. (I just did this for someone). The posts may be out of date, but they might be able to find a job that is new. Call up the hiring manager, or anyone in the company, and ask about what kind of stuff they do that might be interesting.
This won’t work 100% of the time of course, or even 10% of the time, but it puts you above the random resumes. Personal contact does work. Someone I was on an industry committee with sent me his resume. As I was reading it a manager came in looking for my help in defining the requirements for an opening he had. I showed him the resume, which was a perfect match, and bingo, the guy was hired in a few days.
Oh, and don’t worry too much about bugging the managers. I’m pretty visible in my field, and no one calls me. Call, don’t email - it gets a lot more attention. You can email your resume if there is a match. People love talking about their jobs, after all.
I think this will work even if the job is fairly generic. If a manager could hire anyone, who would they choose - a random person from a resume pile, or someone with the initiative to actually call?