To answer this question as broadly as possible I have foundthis really nice essay by a lawyer, Peter Johnson, which is itself well referenced. It starts by giving exemples of:
How it help unify languages:
Geoffrey Chaucer's Canterbury Tales (1387) and Giovanni Boccaccio's Decameron (1349-51), larded with the sexy and the scatological, passed in manuscript from hand to hand and read aloud to a largely illiterate populace, helped create national languages in both countries. [i.e. England Italy]
How it popularized the printing press:
The printing press appeared a half-century after Chaucer's death in 1400[...] twp less noble works did more to popularize print and bring literacy to the masses than the scholarly works. These were Pietro Aretino's Postures (1524)(14) and Francois Rabelais' Gargantua and Pantagruel (1530-40)
After that it was photography:
Three hundred years after Rabelais, photography became a new medium for porn to exploit . [...] It was not long, however, before the Civil War taught photography two new uses. The first and more famous was the battlefield photography of Mathew Brady. The second, the more infamous, was pornography. Soldiers demanded more than letters from home, they demanded erotica. So great was the traffic to the front, not only of dirty books, but soon of erotic daguerreotypes and photographs, that Congress passed the first U.S. law proscribing obscenity via the mails. Congress, as usual, was late. By the time the bill passed, it was 1865, the war was over, and the boys were home with their pictures in their pockets.
Most of the current book formats:
The later part of the nineteenth century saw the growth of the "dime" novel, a brassy subculture to the mainstream three-volume hardcover that monopolized legitimate fiction. Printed on cheap paper, and hence called "pulp" fiction, early paperbacks included westerns, mysteries, tall tales, foreign-language stories for the growing immigrant market, and, of course, pornography. Increased literacy kept paperbacks thriving, though somewhat scorned, until World War II. Then, suddenly, the paperback's cheapness became its strength: wartime shortages demanded that books be printed cheaply; books shipped wholesale to readers overseas had to be lightweight. Paperbacks filled both bills. A government-financed publishing project, the Armed Services Editions, adopted "pulp" technology wholesale,(31) and, after the war, the paperback became the legitimate heir to publishing's crown. Here, then, is a true example of pornography actually developing a new technology that, first, the government (no less) and then the legitimate market adopted whole.
Cable companies:
When cable systems began competing to wireup entire communities, one of the things communities demanded was leased- or public-access channels, to keep the cable operator from entirely dominating local programming. What they wanted was worthy alternative programming produced by local civic and educational groups. What they got was porn. Midnight Blue, produced by Screw magazine, is one of leased access' longest running shows. So are the offerings of ecdysiast Robin Byrd and Lou Maletta of the Gay Cable Network.
