Bits and pieces of this idea have been rolling around in my mind for a while... but with the recent Google Video reaching the light of day that indicates the big G has already thought about how to manipulate the populus, this becomes a bit more relevant and perhaps moving closer to a must have.
I think it would be not only interesting, but exceedingly useful, to create some sort of distributed search tool that is curated (either deliberately or automatically or some combination of the two) by the people in your connections list and perhaps somehow distributed among various hubs.
It could be passively "curated" by somehow indexing items that have been shared by your connections. When a link is shared by a connection, the shared page is crawled and indexed and either the index meta-data is shared with each hub and/or user. Another way would be some sort of knowledge domain token is passed as a pointer to the originating hub so that queries for that knowledge domain get passed to that hub and results are collated by the "querying" hub. These are just prelimiary thoughts - and a million ideas are jumbled in my head about the HOW to do this in combination with maintaining privacy and data security.
Ideally there would be a way to adjust results based either on some sort of reputation scale (able to be individualized by the one performing the query - perhaps somehow related to affinity - or maybe based on some other metric yet to be created) perhaps also including some sort of "evaluation" of the quality of the link by the person adding it.
Anyway - some random thoughts. Anyone have others?