When you've got a big pile of ideas and need to narrow them down so you can focus on a few.

Group the ideas according to how much effort they will require to deliver and by how much impact they have.

1. Either gather together the existing ideas or have a brain-storm and make some. Write a name/description of each on a real or virtual small post-it.
2. Draw a crosshair graph, nice and large on a real or virtual whiteboard.
3. Label the horizontal line "impact" with "low" on one end and "High" on the other. Label the vertical line "Effort" with "High" on one end and "Low" on the other.
4. Go through each idea in turn, and as a group decide how much effort is involved and what the impact will be. Place each idea accordingly on the graph.
5. If there are still too many ideas to choose from in a cluster then further narrow it down by ranking those ideas on a third dimension (e.g. "originality").