Search-solutions has a couple of customers that run Sitecore together with Solr.
These customers use our expertise on Solr to make sure they get the best search-results within their Sitecore implementation.
We've published a simple yet useful implementation of a solr querycomponent that enables the use of server side query (ssq) templates. The jar and source code is available on github.
The purpose of this component is to store solr queries in the solr (server side) configuration. This hides solr query complexity for the clients and avoids the distribution of complex queries on client side.
This results in easier maintenance and upgrade of your solr index and solr implementation: your clients will only be affected when the API has changed, not when the index has changed.