I have a lot of orphan blocks from doing the free monthly block challenge at my LQS. Every so often I sash a dozen and make a top for a charity quilt, then take to the guild (there are volunteer quilters) for the comfort quilt program. Swapping might be fun to put together a more coordinated group.
Maybe people would want to swap themes (like patriotic or childrens novelty) or colors. Maybe limited to size (12 1/2")?