Expand the challenge model so this innovation community is always available. A person or team with a new idea could post an idea at any time, and have an amazing human-centered, open innovation community to work with to develop the concept. The human-centered design tools that we use in challenges would be available to help inspire and structure work. The community's questions and ideas would be there to suggest tests and prototypes. And the community would be available to respond to discoveries from prototyping. This diverse network would serve in many ways as an always-on, open innovation accelerator for mission-driven ideas.
OpenIDEO might define four or five standing issue areas that it wants to impact in the world, so the community isn't too broad vs. deep, and the community can amass expertise over time. For example, the "standing communities" might be focused on education, health, poverty, and climate. Each area could have a Research and an Ideas area. Research could accumulate over time and support anyone working on this issue. Ideas would accumulate over time as well, also providing inspiration.
An open door generally isn't enough to create an active open innovation community. OpenIDEO does have the advantage of a well-established and active community to support this "always on" model. Most innovation communities use challenges / campaigns to drive activity. A standing community might kickoff with a Research phase to get started, or OpenIDEO might seed each space via a full challenge to start. OpenIDEO periodically could run specific challenges in these spaces too, since they align with big issues that OpenIDEO and sponsors care about. The OpenIDEO team could watch and participate in the spaces, and promote "selected contributions" to engage the broader community. OpenIDEO might also run Refinement / Top Idea "events" to build on the organic activity in the topic area. This could periodically boost engagement with posted ideas, create periods of more intense movement for the idea creators, and connect top ideas from this organic activity to future phases (such as path to pitch, funding, impact support, etc.).