Lean Coffee is a structured, agenda-less meeting approach that is effective for getting people to create and share ideas. I really like this approach when dealing with slightly larger groups that have some common goal or project but a lot of different directions or areas of focus.
I also think this is a great tool for brainstorming around a specific topic in respect to organizational strategy and direction. By giving people a prompt ahead of time to think about they can come prepared to pitch and bring topics–IE If you were give 10,000 for a program, what program would you want to build and why? or What do you think is the biggest challenging facing our organization right now? / What problem do you think is our number 1 obstacle that needs solving? or etc.