The porn industry has always been on the forefront of technological progress, pushing us into the world of video chat, streaming media, broadband access and online payment systems. It appears they're also getting into the e-book business.

Both Amazon and Barnes & Noble have clear content policies against porn in self-published titles, and Amazon employs both automated and human filters to keep sexxy content out of their marketplace. Yet porn is flourishing on both sites.

A quick search for "erotica" in the Kindle Store brings up 400 pages worth of titles, despite the fact that Amazon refuses to oblige me by autofilling the search bar. Those books range from poorly-written short erotica to pages of low-resolution still images, both often snagged from easily available sources around the internet.