Shortly after becoming deputy mayor in New York City, I attended a community meeting in Staten Island with Mayor Michael Bloomberg. During the question-and-answer period, one woman raised her hand — not to complain but to offer a suggestion about how to improve a nearby park.

It turns out that she was one of the community's preeminent volunteers, but her work in that park was hampered by limited access to resources, particularly equipment. As we listened to her describe the situation, another resident said he could provide the tools she needed. Right before my eyes, two New Yorkers had successfully collaborated to improve their community.

Similar moments also occurred during the small weekly breakfasts I hosted throughout the city with community activists. While some of the meetings were merely platforms for passionate complaining, most of them featured constructive dialogues on how to solve local problems. Invariably, the residents engaged not just with me but with each other to discuss how, working together, their neighborhood could be improved.

From constructive moments like these, the seeds of powerful ideas were planted. I had witnessed productive collaboration taking place simply because a public official convened a meeting and asked for honest input. These meetings removed the layers of bureaucracy that often screen out innovative ideas, facilitated feedback about the quality of city services, and, most important, unlocked often simple and inexpensive solutions to quality-of-life issues.

But translating these ideas into action requires collaboration — not only among community activists but also among public agencies. Too often, good ideas fail to gain traction because they emerge in isolation and encounter obstacles, such as the need for certain resources or help from a particular city agency, or worse yet, for a coordinated response from multiple agencies. The enormous challenges of finding official champions for these kinds of proposals and of navigating the labyrinth of government can discourage individuals from pursuing action. When the light bulb goes on in someone's head, there needs to be an easy way to put that idea into circulation and to help it get the support it needs. Clearly, having a top city official meet with residents in groups of 10 is a physically impractical idea in most cities.

How then can government actively facilitate grassroots change? In New York City, Change by Us NYC invites New Yorkers to join a social network that connects them to other motivated individuals in their neighborhoods and across the city. On the site, members can post ideas, join or create project teams, and easily access the resources of city agencies and community-based organizations. Users can join others in their neighborhood or by subject and can easily engage city officials assigned to participating in the discussion.

Change by Us NYC is not intended to be a virtual suggestion box for citizens—the city already has one of those. Rather, it recognizes the unique power of social networking to link resources and ideas from multiple sources and mix them together to foster collaborative solutions more valuable than the sum of their parts.

Since its launch on July 7, the early results of Change by Us NYC have been promising. In its first month, the site registered more than 1,100 users, had more than 1,500 ideas posted and saw more than 185 projects created across the city, from starting a community composting station in a Manhattan neighborhood, to beautifying and building a garden in a churchyard in Fort Greene, to constructing greenhouses on school roofs that can turn into classrooms.

The city also is supporting the implementation of up to 40 projects by offering mini-grants of between $500 and $1,000. Change by Us NYC is currently focused on environmental-sustainability ideas and projects, but it is a platform that can be expanded to additional areas of collaboration as the site picks up steam.

One area where the city is particularly encouraging community groups to get involved is on improving the city's management of combined sewer overflows (CSOs). New York, like many other older cities, faces substantial Environmental Protection Agency mandates for reducing CSOs. The city's Green Infrastructure Plan moves the city from investing in underground gray solutions—the typical concrete tunnels that collect and transport excess water—to greener solutions that would reduce CSOs through strategies like building permeable surfaces to better absorb runoff. Through Change by Us NYC, community activists can propose tree plantings, landscaping changes or new retention ponds to strengthen the city's infrastructure in areas most affected by runoff.

Good ideas need a fertile and supportive environment in which to grow. Change by Us NYC provides an important first step in what I hope will become a movement in government that recognizes the value of leveraging the ideas of everyday citizens in delivering better public services. The seeds of innovation are waiting to be planted — they simply need to reach fertile ground.