Once upon a time, craigslist.org was a little homegrown Web site that won over Bay Area residents by providing a free and friendly place to post classified ads. That little site went on to conquer the world, and now has Web forums for 105 cities and attracts five million postings a month. Soon it will go about conquering outer space.

Seriously.

Recent posters to craigslist may have noticed a little checkbox that asks if it's "ok to transmit this posting into outer space." In a few weeks everyone who answered "yes" will have their messages beamed into the heavens by the Florida-based Deep Space Communications Network via a five-meter parabolic dish antenna. A March test transmission of the first 138,000 messages went swimmingly. Act now and you, too, can offer our intergalactic pals a low, low price on your used computer peripherals.

The celestial communications project was born when Craigslist CEO Jim Buckmaster put down the winning bid ($1,225) for a chunk of transmission time the company was auctioning on eBay under the headline "Call an Extraterrestrial." On May 15, the network intends to aim one of its satellite dishes skyward and transmit a video message from craiglist founder Craig Newmark, a clip from the new documentary 24 Hours on Craigslist, and hundreds of thousands of postings—so many that Craigslist has agreed to pay extra to accommodate all of them.

Some of the messages seek extraterrestrial input on science or politics. Berkeley resident Christian Rose posted a question about evolution, wondering if a higher intelligence might weigh in. "It's probably just extra space noise, but you never know," he says. Alameda's Kerry Sullivan contributed her missive urging the site's users to support an animal-rights cause. "I hope anyone and everyone, from any planet, will help," she says.

It's debatable, though, how many of the site's postings would warrant a second glance by alien ophthalmologic organs—most are just ordinary folks looking for restaurant recommendations or advertising apartments. San Francisco's Linda Atkins, who posted a decidedly Earth-centric gripe about the bike parking situation outside Rainbow Grocery, decided to zap it into space anyway. "I just happened to be posting and thought, Why not?" she says. "I'm still waiting by the edge of the Earth—which I think is the equivalent of waiting beside the phone—for an answer."

All of this has provided much amusement for founder Newmark, who notes that most of the interest has been concentrated in the personals section. "A lot of people are interested in interspecies dating," he says. "Of course, we're no stranger to that in the Bay Area. There have been specialized items in which people expressed their desires in terms of tentacles and that kind of thing."

To wit, an ad with the heading "Wanted: Extraterrestrial Girlfriend" specifies a preference for a space girl "at least 50% humanoid" who breathes oxygen. "Let's go to Pluto or the Dogstar, or some nice blue-green planet where they have no literal translation of 'oil war'; drink the dew of immortality and have weird sex," it beckons. "Your pic gets mine."

The person behind "Homosapien [sic] for Extra Terrestrial" was more concerned with the logistics of interstellar dating: "It would be cool if you had like a transporter or something because I'm not good with LDR's [long distance relationships]. Either that, or a spaceship that goes really really fast but somehow doesn't affect the space/time continuum. I don't want to go see you for the night/weekend only to come back to find out that everybody I know is dead and 400 years have passed. That would suck."

To date, earthlings have made few purposeful efforts to talk to the stars, and, unlike the somewhat random craigslist messages, those prior missives were meticulously crafted. In 1974, scientists made their first attempt to communicate with any intelligent life out there. Their brief message, beamed from the Arecibo radio telescope in Puerto Rico towards the Messier 13 globular cluster 25,000 light-years away, contained information on our basic numbering system, the atomic numbers of key elements, chemical formulas of the four DNA building blocks, the average human height, and the Earth's population; it also portrayed a double-helix, a human being, and our location in the solar system.

Three years later, the "Golden Records" carried aboard the Voyager 1 and 2 space probes showed our solar system's location relative to fourteen pulsars, and included images and sounds of life on Earth, plus spoken greetings in 55 languages and a recorded message from then-president Jimmy Carter: "This is a present from a small and distant world ... We are attempting to survive our time so that we may live into yours. We hope someday, having solved the problems we face, to join a community of galactic civilizations."

Even radio and TV broadcasts, which constantly emanate from our planet, at least contain scripted portrayals of human behavior. Craigslist postings, by contrast, are a mish-mash of the mundane, the incessant babble of people trying to unload old sofas or instigate three-ways. Still, one could argue that the conglomeration of so much trivial and often conflicting information says more about the human condition than the Golden Records ever could. Newmark gravely ponders the import of what his company is doing, and concludes that the site's messages indeed say something crucial about humans: "Aside from dating," he deadpans, "they're interested in IKEA furniture."

The project has also proven that people dig the idea of broadcasting into space, enough to convince Deep Space Communications Network that it has hit on a viable business model. The eBay auction was the network's test to see if anyone would bite. Now, the company reports, it is fielding about a hundred requests for transmissions a day, among them proposals to beam up the trailer for the upcoming War of the Worlds remake, and to starcast a new CD by Florida band Black Eyed Soul, which is about to release its sixth album despite playing what singer/guitarist Andrew Marcus calls "the least popular style of music you could be playing right now." (Americana roots rock, à la Tom Petty, he clarifies.) "We've been snubbed quite a bit by the industry here on Earth—why not see if there's anybody in deep space with any taste?" he asks.

To those who fear that beaming this sort of stuff into space could inspire the laser fire of aliens who detest roots rock, or who got the wrong idea from the War of the Worlds trailer, or who, perhaps, we inadvertently alerted to a new food source, Deep Space Communications Network general manager Jim Lewis says not to worry. The odds are slim that anything will pick up the signal. The intact broadcast should only travel one to three light-years—5.8 to 17.4 trillion miles. In galactic distances, that's chump change. "That takes us outside of our solar system, but we may fall short of the closest star, which is about 4.2 light-years from Earth," Lewis says.

At best, a passing starcruiser might receive the signal. What's more, any would-be listeners would need satellite dishes similar to ours; they'd have to tune in at just the right place, time, and frequency; and, of course, they'd need auditory organs, not to mention language skills. "If they are some kind of microbe or amoeba, our signal might hit them but they're not going to receive it," Lewis says.

Nevertheless, here's a date for your Palm Pilot: Should the messages be received at the outer reaches of the transmission range, we could get a message back in about eight years. That's not counting the responses Newmark has already found on the site claiming to be from Mars, thanking earthlings for "the cool go-karts."

"The chances are pretty much close to zero of actual alien contact," he concedes, but the "list in space" service has been so well received—about 10 percent of craigslist posters are opting in—that the company may make it an ongoing feature, at least until it finds a better way to blast classifieds into the nether reaches of the universe. "I think we really need some kind of faster-than-light gateway, because radio communications are limited by the speed of light," Newmark gripes. "The speed of light is so 21st Century."