Think that you have diffent grouping over your products. Like products grouped by poduct types and products group by producers. But you have just one catalog block that displays all the categories within one block.
Here is just an example of having two group in one catalog.
- products - product category 1 - product 1 - product 1 - product category 2 - product 1 - product 1 -producer - producer category 1 - product 1 - product 1 - producer category 2 - product 1 - product 1
With Multi Catalog Menu module you can compose 1 or up to 5 diffent blocks and just configure these blocks to show the related group term id with its children.
If you like please download and give a try. You will find a readme.txt within the zip file. By the way this module tested with beta5.