object-oriented DBMS
Tangram is an object-relational mapper. It makes objects persist in relational databases, and provides powerful facilities for retrieving and filtering them. Tangram fully supports object-oriented programming, including polymorphism, multiple inheritance and collections. It does so in an orthogonal fashion, that is, it doesn't require your classes to implement support functions nor inherit from a utility class.
Homepage: http://tangram.utsl.gen.nz/