VistaDB

I came across an embedded database that seems cool.

VistaDB 3.0 is the world's first fully managed and typesafe embedded SQL database engine built for Microsoft .NET, Compact Framework and Mono. Developers can build embedded cross-platform ASP.NET and WinForms database applications for desktops, mobile devices and web servers.

Read more at their homepage; http://www.vistadb.net