It was such a simple idea, Ginger Runes Najar couldn’t believe no one had tried it before.

It’s such a good idea that publishers, theaters and bookstore chains are now falling all over themselves to get in on it.

Najar opened Reel Books, and sells filmbiz-related books in … theaters!

Since last November, Najar has been running the bright red kiosk in the lobby of the Sony theaters at 68th and Broadway, offering everything from the latest Leonardo DiCaprio fan book to Victor Hugo’s “Les Miserables” (a tie-in to the current Liam Neeson-starrer) to a biography of Fellini.

“The thinking was always that books didn’t sell well when taken out of the bookstore environment, but now theater owners are realizing what a fabulous retail space they have, and books are just a natural,” says Najar, a self-proclaimed “book brat” who grew up in the publishing biz, eventually becoming publisher of her family’s Philosophical Library Publishing Co.

With movie tie-in books more popular than ever, and book publishers always looking for new ways to hawk their wares, Reel Books hit a marketing nerve, and Najar now regularly fields calls from publishers who want their books displayed, while chatting amiably with customers and ringing up sales at her kiosk.

In 4-1/2 months, Najar (who has two private investors) has already “broken even.” And she has started some new store initiatives, such as a summer Children’s Story Hour tied to hot summer pics and featuring some Gotham-based children’s book authors.

Najar will soon have Reel Books shops set up in Denver, Los Angeles and Orlando theaters, and by the end of summer she hopes to have finalized a deal with one or more of “several bookstore chains” looking to build on the idea.

“It could be a leasing or franchising kind of scenario. I’m not interested in selling the idea outright at this point, and I want Reel Books to remain independent,” she says, adding that the big chains are swallowing up enough indie booksellers.

“I’d like to see that trend reversed.”