When former Wall Street banker Jennie Nevin moved from New York to Denver last year, she brought a great idea with her. Like its flagship in Brooklyn, Green Spaces is a collective workspace where eco-preneurs share space, vision and inspiration — as well as copy machines, recycling bins, land lines and even interns. Located in an appealingly open former warehouse in the RiNo district, Green Spaces triples as a workplace (desks and cubicles are rented by the month), event hall and gallery of furniture and art fashioned from reclaimed materials. Most excitingly, it's an incubator for some of the city's forward-thinking new businesses. Open to everyone who's willing to maintain a code of sustainable practice in the workplace, Green Spaces is an idea that's catching on: The next one sprouts in Los Angeles later this year.