I'm looking into some example UI on top of Solr that show of the functionality available in a demo, like e.g. drill down faceted search. I found Blacklight, which looks intensively interesting. Is there any other software that is worth researching or is Blacklight definitive the way to go? Thanks.
Have you looked at using the Velocity templating built into Solr? You can find more about "Solritas" here: http://wiki.apache.org/solr/Solritas
I am about to put together a demo Solr site for a presentation, and am going down the Solritas route. You get faceting, clustering, and more! And no extra server to run.