IT'S HALLOWEEN AT 826 Valencia. The wench behind the register at the Pirate Store wears a wig of glossy braids wired Pippi Longstocking-style, an eye patch pushed up above her eye. Following her elaborate instructions, I wind through rooms stuffed with costumed children and computers until I find a room toppling with paper clutter and rooted with desks containing busy people. It's McSweeney's publishing, home of the increasingly whimsical McSweeney's literary journal, plus the fully operating press of the same name, which this year churned out around 15 books.

"We should have done fewer," managing editor Eli Horowitz sighs. Spread on a picnic table before him are the fruits of so much labor, a pile of books that includes a fashion guide ostensibly penned by the pope; baby books that coax toddlers to mix cocktails for their parents; a dense oral history documenting the experiences of people wrongfully convicted of crimes in America; a McSweeney's greatest-hits compilation featuring writings from the first 10 issues; an interactive young-adult anthology to benefit the 826 tutoring center in New York; and the latest McSweeney's quarterly, convincingly designed to look like the mailbox contents of one Maria Vasquez, complete with junk mail, catalogs, magazine subscriptions, and letters.

"Barnes and Noble and Borders have refused to carry it, 'cause it's too weird," Horowitz says. "Apparently even some indie stores have been befuddled. It's befuddling." He takes it apart and gives me a tour of it. "This is a catalog of clothing for multiple wearers," he explains, holding up a full-color mailer featuring people wearing odd group outfits: exercise pants for two, a windbreaker for three, a knitted afghan "couch dress," and, Horowitz says, "a special hugging coat, with extra arms coming out the back."

"This is a catalog of sausage gift baskets," he says of "Tyrolean Harvest," a Harry and David-esque parody full of photos of essentially the same meaty gift basket. He lifts a copy of Yeti Researcher: The Magazine for the Society for Cryptic Hominid Investigation from the pile. "It's very serious," he promises. "There's all sorts of real science in here. There are these real debates – if you find the Yeti, should you kill it or not? Even some people who love it say the only way it will get endangered species status is if you can provide a specimen." He shrugs sadly. The controversy is explored in the article "Gunning for the Martyr: A Look at Bigfooting's Biggest Dilemma."

The McSweeney's empire was founded in 1998 in author Dave Egger's apartment. "I think he was procrastinating while he was working on his first book," Horowitz speculates. The first few McSweeney's had simple white covers and were filled with work that glossy magazines had rejected. In 2000 came the launch as an independent press with publication of The Neal Pollack Anthology of American Literature. A scant three years later, and two McSweeney's books – William T. Vollmann's Rising Up and Rising Down and Nick Hornby's Songbook – were finalists for National Book Critics Circle Awards. "That was when it got fully serious," Horowitz says.

The McSweeney's office receives more than 7,000 story submissions a year for its journal; no clear number or method exists for the collecting of book manuscripts. "We are trying to figure out how to do it," Horowitz says, "because I don't want to put up boundaries and make it only agented work, but it's tough, 'cause they're books and they're longer. We're figuring out how to be intelligent gatekeepers."

Currently McSweeney's is anticipating the release of the book Surviving Justice: America's Wrongfully Convicted and Exonerated, a collection of oral histories coedited by Lola Vollen and Eggers and copublished with the UC Berkeley Graduate School of Journalism. It is the first in a larger oral history series, Voice of Witness, which aims to illuminate human-rights crises around the world; a Hurricane Katrina volume is in the works. McSweeney's is also poised to launch a new DVD magazine, Wholphin ("It's a cross between a whale and a dolphin," editor Brent Hoff explains). Wholphin debuts in December, and the first hit – which includes Spike Jonze's unseen Al Gore documentary, a Turkish sitcom similar to The Jeffersons, and Iranian animation – is free, to be included in McSweeney's and its sister publication, the Believer. After that, you got to subscribe.

"I think we try and focus on ourselves as readers," Horowitz says, getting at what binds such diverse material together. "We publish things that we like to read rather than be driven by ideology or market niche."