I am looking for a small database that can be "embedded" into my Python application without running a separate server, as one can do with SQLite or Metakit. I don't need an SQL database, in fact storing free-form data like Python dictionaries or JSON is preferable.
The other requirement is that to be able to run an instance of the database on a server, and have instances of my application (clients) sync the database with the server (two-way), similar to what CouchDB replication can do.
Is there a database that will do this?
If you don't need an SQL database, what's wrong with CouchDB? You can spawn a local process to serve the DB, and you could easily write a server wrapper to allow only access from your app. I'm not sure about the access story, but I believe the latest Ubuntu uses CouchDB for synchronizeable user-level data.