If you are a blogger you write a lot of content. This content is the life blood of your blog's traffic. Your posts are the main element that brings visitors in and turns visitors into readers.
Since you write all of those posts In the natural process of blogging, it would be marvelous to find ways to reuse it to get even more use from it.
Now when other bloggers read this report some of them will decide they want to put your report on their site for their readers to download. This will advertise your blog to many visitors who might not have known about your blog otherwise. And some of these people will choose to link to your free short reports from their sites too, which will promote your blog even more in an ever widening circle of targeted readers.