Displaying 'Global content' on blogs other than Root

I posted this as part of this 'classifieds' request, but thought it best to throw it out for discussion in regard to other plugins too.

Our multi-site model aims to keep the root blog relatively free of content, and instead, create functional area blogs that contain specific content for our members.

For example we'd like to run individual blogs that pull in global content into their own blog for the following plugins:
*MarketPress - aggregation of our various stores
*Classifieds - aggregation of our member classifieds
*Membership - member management area
*Directory - when its released . Particularly when/if it allows members to add and display listings from their buddypress profile and then be aggregated to the the Directory blog.
*Global Tags
and there maybe others...

So having the option to choose where 'global' content will reside is an advantage.
If this isn't possible, then the other option would be to at least be able to nominate one other blog that would contain all other global content (apart from the root), but the preferred option is to create it as above.

I'm wondering if this request is supported by other members and if so, could it become an option in the plugins' settings rather than having to hack the code of plugins.

I look forward to any replies. thanks,
Paul