IT'S 10 a.m. on a cloudless, frigid October Monday, and sunlight is pouring into Grist's modern eighth-floor offices, which are a mismatch with the classically ornate Dexter Horton Building. Grist's staff of 20 moved into the airy, 5,000-square-foot space four months ago, and it still has that barely-lived-in look. The unadorned walls are splashed with shades of mango, cornflower, and cream. The beige carpet is spotless. The furniture is IKEA. Like everything in the nonprofit's $2.5 million annual budget, it's paid for by foundation grants, along with a dollop of reader donations and advertising.

Over in the large editorial wing, a windowed space with views of Mount Rainier, Roberts and senior editor Lisa Hymas, both in their early thirties, are supposed to be finalizing headlines for the Daily Grist, which is due to be posted on the home page and sent out in an e-mail newsletter in 15 minutes. Roberts, artistically unkempt, wears a T-shirt emblazoned with a clenched fist and the sunburst slogan SOLAR POWER TO THE PEOPLE! The petite Hymas is braced against the chill in a heavy turtleneck sweater. They procrastinate by giving me a primer on Daily Grist headline history, delivered with the kind of freakish conversational coordination found in seven-year-old twins.

"It was a spur-of-the-moment idea," Roberts says, "but it's since become the calling card of the entire Grist operation."

"It was kind of a fluke," says Hymas.

"A fateful decision—"

"Which haunts us to this day."

"It seemed like a good idea five years ago," sighs Roberts. "But 5,000 e-mails later . . ."

"There are only so many whale puns—" says Hymas.

"Or Canada puns—"

"Or forest puns. We just keep hoping for a new global calamity that we haven't punned out. Climate change is getting a little tough."

"Somebody needs to screw up something else."

Roberts and Hymas, one-fourth of Grist's eight-person in-house editorial team, typify the talent Giller has cultivated since founding the site in 1999. Roberts was hired as an assistant editor in 2003, his salary provided in part by $35,000 in reader donations from the Grist Grapefruit Challenge, a pledge drive during which staffers ate nothing but grapefruit for two weeks. He quickly became a force behind the Gristmill blog and is now one of the site's big guns: In 2006, he interviewed both Al Gore, who talked about An Inconvenient Truth, and Barack Obama, who discussed fuel-economy standards.

Hymas, who's been with Grist off and on since the beginning, focuses on the site's original content, which includes Muckraker, a political dispatch by Nashville-based Amanda Griscom Little (who also pens Outside's Code Green column); Victual Reality, a weekly column about organic edibles; the Grist List, which celebrates green celebrities; and Ask Umbra.

Giller, meanwhile, spends much of his time selling donors on his ambitious expansion plans, which he refers to as Grist 2.0. His goal is to triple the site's current readership by ramping up its lifestyle offerings—adding a broad range of product reviews, along with personal ads and classifieds— in a bid to appeal to the growing legion of sustainability-minded shoppers who support America's $30 billion green market.

The buildup, which Giller says will require $10 million in new funding, will put Grist in competition for readers and ad dollars with for-profit sites like TreeHugger and Ideal Bite, which have developed robust followings by blogging about eco-friendly products. (Grist has collaborated with both sites on cross-promotions and content development.) Giller also wants to pump up Grist's news resources. He envisions Grist as a one-stop portal that attracts and serves consumers, then uses serious journalism to convert them into activists.

At the moment, though, Roberts and Hymas still have to finish their headlines. Roberts is sprawled on a swivel chair behind Hymas, who's seated at her Dell. First up is a promotional blurb seeking free labor for a Grist reader party next month in San Francisco. After several attempts to splice "volunteer" into the title of the Showtime hit Queer as Folk, inspiration strikes.

Sort of. They come up with: "We're Here. Volunteer. Get Used to It."

"Do it," Roberts says, before telling me that part of his job is "to force Lisa to accept sub-optimal headlines in the service of getting the e-mail out."

The struggle to save a rare Japanese wildcat gets slugged "Goodbye Kitty," and advice on greening Halloween becomes "Boo-ty Call." But there's one title that won't yield: a Grist interview with a woman named Billie Karel, who's working to reduce schoolkids' exposure to pesticides in North Carolina.

"Spray," Hymas suggests. "You could play on the spray."

"Don't Save a Sprayer for Me Now," Roberts says. Then he bursts into a falsetto version of Duran Duran's 1982 hit "Save a Prayer."

They sputter onward for a few minutes before settling on "Say It: Don't Spray It." But, clearly, no one is satisfied. And so, three days later, the second installment of the story is posted under the soap-opera sparkler "The Young and the Pestless."