"As a public company, stock is our currency, " explains the company's chief, Steven Schneider, who took the top job when Zap, which stands for "zero air pollution, " bought Schneider's auto repossession business in 2002.

FORBES: Shock Jocks

You have to understand, after spending 12-15 hours at ground zero, the air in this area is very heavy, it's almost suffocating.

CNN: Steelman and Angeli: Search and rescue at ground zero

For years they were caught up in disputes over whether the air at ground zero was really toxic -- the Environmental Protection Agency long claimed it was safe -- and whether the illnesses could be linked to the attack site.

CNN: 9/11 responders wait for compensation for their illnesses

Chief Executive Daniel Elliott wants to amass emission credits it will get from the California Air Resources Board (CARB) for selling zero-emission vehicles and then sell them to other automakers in danger of falling short of minimum requirements.

FORBES: Magazine Article

Adobe's been trying to get Flash on the iPhone with zero success since Steve Jobs first held the thing in the air in 2007, and it looks like the tension is only going to grow as the iPhone OS moves onto the iPad.

ENGADGET: Adobe on Flash and the iPad: 'Apple is continuing to impose restrictions on their devices'

And as she headed back toward her apartment, four blocks from what was soon to be known as ground zero, the south tower collapsed, sending a plume of debris into the air and straight down her street.

CNN: The story

Just as suddenly the air deadened, and at one point during the night the wind meter read zero.

FORBES: Life

And if air travel is more your speed, why not take to the skies aboard this zero-emission Elektra airplane, which spends its downtime soaking up the suns rays in a solar hangar.

ENGADGET: Inhabitat's Week in Green: electric cars, solar planes, and really sweet lights

Sales of everything, from school satchels to air-conditioners, are at a trickle, and the newspapers are full of advertisements for zero-interest, no-deposit luxury flats.

ECONOMIST: Egypt