If I made a search for "TV" I want to have search filters on the sidebar which gives me options like following...
Sony (10)
Samsung(5)
Panasonic(3)
When I click on SONY, it will only return Sony tvs.
This is called 'faceting'. Check out Facets in SolrNet and Solr faceting overview.
Also, the SolrNet sample app implements facets, you can use it for guidance.