Block Queue | drupal.org
Block Queue solves one of the major shortcomings of Drupal 6 block management: the ability to easily re-use blocks in different regions, on different pages, with arbitrary ordering.
Block Queue allows users to create "queues" of blocks much like Nodequeue allows to create queues of nodes: by adding arbitrary blocks to the queue and ordering them any way necessary. Queue size can be limited.
Queues are exposed as blocks and can be easily included in Drupal regions.
Always felt that blocks needed a meta- or group concept, so that you can say "these five blocks display together" and turn them all on or off together per page, or move between regions as you change layout over time. I wonder if it helps with the problem of showing a block in say, the left sidebar on the front page and pages X and Y but the right sidebar on all node/nid pages and page Z.