The description of db4o for Mono - Play With New Friends
db4o (database for objects) is the open source object database for Mono. Free software, available under the GPL and under a commercial license. Persist any object with one line of code. Other features are object-oriented replication, native queries, and automatic schema recognition. Ideal for embedded use, e.g., in software running on mobile or medical devices, in packaged software, and for real-time systems.