With music tracks running into "the tens of millions," creators and marketers strive to find ways to make it easier for people to find things. In what's probably the best chapter in the book, Jennings highlights a commercial venture called The Music Genome Project, which "cracks the code" of content and recommends music that users "don't yet know but may wish to buy."

The online music service Pandora uses this method. Based on listening preferences, Pandora recommends songs with similar traits, such as the sex of the lead vocalist, "use of modal harmonies," "emphasis on instrumental performance," and "minor key tonality." While the average listener may be unfamiliar with some of these terms and have little interest in breaking down music this way, creators and marketers may find the project quite useful.

"By analyzing everything from the latest new releases to Long Tail obscurities," Jennings writes, "we could filter out all the stuff that won't appeal to you, leaving just the essence that will."

Jennings explains the role of "intermediaries" like eMusic and All Media Guide and professional reviewers and editors who help consumers navigate through a sea of entertainment products. In the digital age, the professionals serve more as a "guide on the side" than a "sage on the stage" as they've traditionally done. With tools like blogs and wikis, the days of gatekeepers are gone. Former gatekeepers and present intermediaries are using the new media to facilitate discoveries.

Although the central focus of the book is on music discovery, the "rock 'n' roll" part of the title is a reference to the spirit of self-expression, rebellion, and a do-it-yourself attitude toward discovery in general. It conveys the sense that this energy "comes from the hips as well as the head—discovery and exploration are never ending."

Net, Blogs and Rock 'n' Roll will help you understand the challenges of digital discovery and inspire you to become part of the solution.