Or even a current event.
One of the best ways to promote your book is to write an essay/article piggybacking on something hot -- and/or related -- to your topic.
For example, I know someone who wrote a book about fly fishing several years ago. He keeps saying he wants to revive interest. I had to sit him down and "beg" him to write something (op-ed, essay, etc) using Henry Winkler's new fly fishing memoir as a springboard. He hemmed and hawed. He doesn't want to have "resort to that." Apparently, he wants people to just "know" or "hear" about his book. He suffers from what I call, "If I write it they will come" syndrome. You must promote.
I told him "The Fonz" gave him a gift on a silver platter and he better jump on it before HW's book is old news. Some people don't know an opportunity when they see it.
FIY: I sold a dozen copies of my novel, FAT CHICK, hours after an article I wrote about splitting the check at group dinners appeared in the NYTimes Complaint Box.
Causes Lorraine Merkl Supports
The Legal Aid Society
The Inner-City Scholarship Fund