The perfect cover letter

Recently a friend of mine applied for a new job. Since he did not know anybody at the company he realized he needed a good cover letter to get through the first filtering and get the recruiter's attention. And so he did...

The cover letter he sent with his resume as not the standard this-is-why-I'm-awesome-and-why-I-love-your-company letter. or actually it started out like that for about half a page. Then it changed. The company he was interested in is running a service with a lot of users. So most of the cover letter (and this was a multi-page cover letter which normally is bad) actually described how my friend assumed the service worked and how he reverse engineered the protocol looking at fiddler traces confirming and updating his hypothesis. He heard back from the company withing a few hours and eventually got the job.

This cover letter was almost perfect in my mind. It is obviously showing interest in the company and showing off some skills that may or may not be applicable to the job. The only thing I would change would be to remove all the regular cover letter stuff or at least put it at the end. Because if you reverse engineer a protocol you don't want the recruiter to miss that.