Lotus blossom
The lotus blossom is an ideation technic where you explore a topic by looking at the related branches, and for each branch you explore more topics again.
Basically, it's about using a mind mapping of a topic and then use the elements of this map to find new ideas as new related topics come out.
You can again use this technic in two ways:
More constraint
Use a centrale topic, force the people to find 8 related themes, and for each 8 related theme find 8 related themes. From there you ask participants to come with one idea for each of the 64 end topics.
Free mind mapping
Just sketch out freely and as you sketch out how the topic is linked with other topics write down ideas as they emerge. This needs a more seasoned facilitator who can ask questions like: what happens if we take this topic and this topic (on another part of the map) and bring them together?