Four nonprofits - Global Kids, Commonwealth Islands, ISTE Islands, and Nonprofit Commons - are using the virtual world of Second Life to build online communities and further their missions. The document provides an overview of Second Life, including how to sign up, customize an avatar, communicate, explore the virtual world, and build structures. It also discusses the costs associated with Second Life and provides examples of how the four nonprofits are utilizing the platform to engage members and advance their causes.