Too many topics, too little time

Joel on Software: “Here's the thing: the very best candidates have come to realize that they have a choice of where to work, and when they apply for a job, they are applying because there's something intriguing about that particular job, not because they'll take any work that comes along. And you can see it in their cover letters. For example, if I were to see something like “I'm happy where I am, but I've always wanted to move to New York and if Fog Creek is anything like you describe it on your website, it sounds like a great place” you would sound a lot more desirable than someone who writes, “You will find that I am a very hard worker.”

[Poorbuthappy Guide to Ease]

yes, well, i must admit that I've had the best luck using a slightly personalized version of a standard letter. I think that the more that you write, the less chance you actually have of attaining the position because there is more information by which to rule you out of competition.