PHOTO BY SAUL BROMBERGER AND SANDRA HOOVER

"Juxtaposition," "serendipity," "appropriation," and "collaboration" are all words that come up frequently when you talk to Rick and Megan Prelinger about the Prelinger Library.

Tucked above a SoMa carpet store, the space ("a free offering, an installation, a workshop, and an extension of our living room," according to the handout given to visitors) is stuffed floor-to-ceiling with books, maps, magazines, and other ephemera. It is a place where artists, students, teachers, architects, T-shirt makers — basically anyone with a curious, creative mind — can seek information and inspiration. Visitors are encouraged to photograph, copy, and scan materials for future use in their own projects.

"This is a completely unconventional library," Rick says. "It's much more a place where serendipity rules."

A certain magic comes courtesy of the library's unconventional shelving system, designed by Megan to maximize what she calls "browsing-based discoveries." It's based on a continuum of ideas and interests, not Dewey Decimals. In a section dedicated to the American South, for example, a dusty government tome about Georgia's river system might nestle next to a paperback copy of Deliverance.

"[Library visitors] tend to start going where they think they're headed," Megan said. "Then they find something they'd never seen before, and they just go in a different direction. They come out going, "Wow! I thought I was looking for this, but I found this.'<0x2009>"

Opened to the public in June 2004, the Prelinger is tailored to its current location. Though the fit is snug, Prelingers have no plans to upsize. "The collection is composed in such a way that there's a relationship between the aisles," Rick explains.

But the collection is anything but static. In addition to what they call the "user-based chaos" that arises when visitors remove and replace books on the shelves, the Prelingers are constantly adding to, and editing, their highly selective inventory. Subjects range from transportation and land-use to media studies and political history (they joke that the stacks harbor "98 percent bad ideas"). "[The library is] specific to what we're interested in," Rick says. "But we're interested in a lot of things."

The Prelinger also boasts an online component composed of thousands of digital books that may be downloaded for free. Though this represents only a fraction of the physical collection, it's a useful tool for those who can't visit the library in person. As it is, the place has limited hours, and both Prelingers support it with other endeavors.

Megan is also a historian, a wild-bird rehabilitator, and an author; her 2010 release, Another Science Fiction: Advertising the Space Race 1957-62 (Blast Books), is a gorgeous, hefty volume that culls and contextualizes imagery from magazines like Missiles and Rockets, bound editions of which can be admired in the library. Rick is widely known for the Prelinger Archives, a groundbreaking moving image archive he founded in 1983. It eventually grew to include more than 60,000 works — all originally made by amateurs or earmarked for industrial, educational, and advertising use. Much of it was acquired by the Library of Congress in 2002 and 2003 (some 2,500 titles are also available online). The archive inspired Rick's 2004 collage film, Panorama Ephemera, as well as his popular "Lost Landscapes" presentations, which meld lively discussions about history with found footage.

Along those lines, the Prelingers have a new-old passion: home movies. "Megan and I now run a really fast-growing and exciting home movie collection," Rick says. "Home movies — that's the only cinema that matters for me. Each one is unique. We think we understand home movies, but they're shallow and deep at the same time."