Crowd sourced maps rely on volunteers to help identify features using online tools and satellite images. Examples include identifying Martian craters for NASA, searching satellite images to find Steve Fossett's missing plane, and creating maps during disasters like Hurricane Katrina to share local information. Mobile devices allow real-time crowd sourced data through social media like Twitter to map things like snow levels. While crowd sourcing has great potential, challenges exist with ensuring full coverage over time and maintaining accuracy of the data.