podcast: BrightstarDB, an open source NoSQL .NET database with Kal Ahmed on the Hanselminutes Technology Podcast
"A native RDF database for the .NET platform"
A NoSQL view of Semantic Web "triple store"
It is already 15 yeast from original RDF introduction.
The ideas of Semantic web are used in search engines
and there was a lot of research,
but not significant usage on Web as originally intended for metadata.
Now it may be useful for data, in particular free-formed, flexible schema.
In this case this NoSQL database got Scott's attention
likely because it can also run on mobile devices
(by using Xamarin on iOS and Android also),
as well as on Windows, servers and even on Linux by running on Mono.
MIT license open source, Linq and even Entity Framework interface.