While video-game players are familiar with the gaming site Humble Bundle, e-book readers will hear a lot more about it in the coming months. Humble Bundle is a Web site that bundles digital games and, for a two-week period, lets users pay what they wish for the bundle, splitting the payment between publisher, a charity of choice, and Humble Bundle itself. The site has experimented with three book-related bundle promotions—two with e-books, and one with audiobooks. The bundles were downloaded more than 200,000 times, generated more than $2 million, and attracted hordes of new readers for the authors involved.

Allowing customers to pay whatever they wish may sound risky, but Humble Bundle, which is based in San Francisco and has about 40 employees, has used the model to create a unique promotional platform. The site was launched by two game developers, John Graham and Jeffrey Rosen, as a promotional platform designed to attract attention to their games. Humble Bundle’s promotions attract millions of fans each week—alerted by a twice-weekly newsletter that goes out to four million subscribers—and the company wants to make e-books a regular promotion. The site also has a stand-alone online store that sells a variety of content at list price, as well as the previously bundled content at regular fixed prices.

Kelley Allen, recently hired by Humble Bundle as director of e-books, shared some overall data about Humble Bundle games during a meeting at the PW offices: overall, the site has sold more than 15 million bundles, generated more than $80 million in revenue, and raised more than $30 million for charity (charities have included Red Cross, the Electronic Frontier Foundation, and Human Rights Campaign).

Here’s how it works: developers/publishers bundle digital titles—usually about five or six—without DRM. Consumers can pay what they wish for these bundles; the payment is divided into three default settings (65% to creator, 20% to any charity, and a 15% “tip” to Humble Bundle), and consumers can adjust those splits to any ratio they want. Allen said most consumers never touch the presets, so generally all parties receive something.

But that’s not all. The consumer can elect to pay a little more than the average donation and unlock even more quality content, usually a bundle of four or five or more titles. While digital games attract the bulk of the site’s traffic, Kelley says books are attractive: the average price offered for games is $5.67; e-books average $12.53. Kelly also noted that 77% of the fans are ages 18–34, and 25% of all visitors to the site make a purchase.

After launching three book-related bundles, Humble Bundle is looking to offer e-book and audiobook bundles on a regular basis. “Humble Bundle’s founders said this should work with anything digital,” Allen said. “E-books won’t be as big as games, but there’s no reason why they can’t be significant.” She added, “People on our lists are gamers and some are into reading science fiction and fantasy and we’d love to attract readers who are into games.”

Humble Bundle’s two e-book promotions were organized by novelist Cory Doctorow, attracted to the effort by the “pay what you wish” format, as well as the lack of DRM. The first bundle in 2012 included six books, among them Doctorow’s Little Brother, Wil Wheaton’s Just a Geek, and Peter Beagle’s The Last Unicorn; the second (in 2013) included Doctorow’s Pirate Cinema, John Scalzi’s Old Man’s War, and Neil Gaiman and Dave McKean’s graphic novel Signal to Noise. Doctorow said the biggest obstacle to the promotion were publishers that refused to participate if the books did not have DRM software, which is intended to prevent digital piracy.

In an e-mail exchange, Doctorow told PW, “All the majors except Macmillan [Doctorow’s publisher, Tor, offers DRM-free e-books] were unwilling to go along with it because we’re DRM-free. But we raised [about] $2 million for our authors in two promos on books that were mostly deep back-catalogue. This was free money, sums that represented a year’s mortgage and more for most of our authors.” Doctorow is a longtime opponent of DRM, who calls its use “a superstition.” He added, “What we were offering was that these authors, and their publishers, stood to make six figures from books whose circulation was making them nothing at all.”

Reached by phone at the company’s San Francisco offices, Steven Kovensky, Humble Bundle v-p, partnerships and strategy, said the site wanted to add more e-book and audiobook bundles, was looking to bundle audiobooks with e-book promotions, and planned to add a page dedicated to e-book/audiobook bundles to the HB site. He said some of Humble Bundle’s partners only sell their content through its fixed price store, and he acknowledged that some publishers and creators “are cautious about the bundling. Some are afraid it will affect regular sales, but it doesn’t.” Kovensky said the site has run tests with big gaming publishers; “they actually see an increase in regular sales [during the promotions] because the bundles generate buzz and send people to buy more fixed price games.”

Allen, whose office is in New York, said she’s been visiting the big trade book publishers to spread the word about Humble Bundle and its potential to attract new readers and generate a sizable revenue stream. “People in publishing don’t know about Humble Bundle,” she said. “Publishers are mostly polite at the beginning, but after they hear about the numbers we get, and the dollars, they begin to pay attention.”