A letter to promote business?

I was wondering, does anyone write a basic letter introducing themselves and their work and mail it randomly to businesses and organizations in their area? I was thinking about doing something like this and attaching a brochure with it to help sell my services. I just don't know what to say. I'm afraid I might come of as annoying and pushy. I guess that is what marketing is all about.

I used to do letters, now I use postcards.

There are several threads about the topic actually, one with examples of many postcards that many of us use.

(I have examples of some forms etc on my resources pages - link is in my signature.)

Thank you Shannon! I found the thread on postcards.