NEW YORK ( MainStreet) — One of the biggest smart phone apps in the world just got a little bit bigger with the addition of movie tickets to Ibotta.

For readers who don't know what it is, Ibotta is an app for cash-back coupons. Restaurants and retailers will put up special deals, say $1 back for each cheeseburger you buy. Users open the app, take a picture of their receipt and get credit for the dollar. Although I was unable to find many deals worth taking advantage around my neighborhood in Chicago, the basic idea is fantastic.

It can effectively reduce the price of shopping or dining out, which helps explain how Ibotta has become one of the most downloaded apps in America.

"We're actually the sixteenth most frequently used mobile application in the U.S., full stop," said Bryan Leach, CEO of Ibotta.

A former trial attorney, Leach released Ibotta onto the market just over a year ago. Today the app has over 2 million subscribers, and the company expects to reach 2.5 million by the end of 2013. Although the incentives are individually small, a dollar here and a dollar there can add up: the company has so far handed out $4.5 million. The result is a system that hands out meaningful amounts of money, but only to committed users.

Now Ibotta has added movie tickets to its list of options, allowing theatergoers to reclaim a dollar or two for every film they see, sometimes more. Just in time too, as prices at the box office have never been higher .

"We've got the first ever mobile application that pays you cash for going to see specific movies," Leach said. "You download the free app, go to the movie theater section and pick the theater you want to go to. Let's say you select Regal. It'll show you a series of titles that you can earn money for watching, and there are interactions -- we call them engagements -- that you participate in to earn more money."

According to Leach, Ibotta's rewards fluctuate based on what the vendor pays. It is, after all, a promotional system; the money into users' PayPal accounts comes from the companies that want to promote their products and brands. Still, he says that the average ticket will kick back a dollar.

Theaters can also offer additional rewards if they choose to, from cash back at the concession stand to rewards for watching movie trailers. For example, the AMC in downtown Chicago has offered $2 for everyone who spends $12 at the concession stand. Unfortunately, at time of writing they're also offering cash back only for people going to see the Hunger Games sequel.

There are also the "engagements" that Leach referred to. Ibotta offers about 20 different ways to earn additional money, although what the user actually sees depends on what local businesses have decided to offer. Engagements can include taking polls, learning brand-related facts or giving user reviews, all for a price.