Interesting (and I think unique) feature added to RavenDB:
RavenDB is a great database for storing documents, and the ability to create indexes on top of documents make extracting information out of the indexes very easy. There are situations, especially for reports, when you still want to use a relational database. The Index Replication Bundle is meant to handle just those scenarios. It is capable of replicating an index a table in a relational database.
Original title and link: RavenDB: Index Replication to Relational Databases (NoSQL databases © myNoSQL)