Community innovation can take three forms: (1) having the community design and develop new products, (2) allowing the community to change and improve existing products, and (3) adjusting an organization's strategy based on community input. Examples of communities innovating new products include Threadless and open-source footwear projects. Communities can change existing products by providing feedback on how to better meet user needs, as seen with News To Me and citizen journalism sites. Prediction markets and bug tracking are examples of communities helping adjust strategies. However, building and maintaining engaged communities poses challenges around moderation, incentivization, and focus.