I always think the cover letter or intro email is one of the hardest things to write. First off it may not be even looked at given how lazy HR or hiring people are these days. Usually they see an email come in, say "Hey another one!", then scan the resume into a flawed computer system the will use factors to discriminate people out of the running for a job. Also, so-called "experts" will tell you conflicting things on how one should be written, how long it should be, etc.
I decided, after enjoying the WWE Network for a couple weeks, that maybe writing one as if I was giving a wrestling "promo" (monologue that is either about the wrestler to make him look good or his enemy to further a storyline).
Obviously I wouldn't be talking trash about the company I'm trying to simply get a response to. It would be in the way some wrestlers used to say "I'm the best wrestler here, and here's why." If you look up some of the most famous wrestlers' work. You'll see what I mean.
At this point it can't hurt trying something new, right?