From the XML definition of your database, DewDrop will generate clean and human-readable SQL DDL code for any supported target database. This means you can define your database just once in XML, and have it work for any database automatically.
kissme is a free (GPLed) Java Virtual Machine. It is being developed on GNU/Linux and can run console java applications. kissme is to be used with the GNU Classpath java class library. kissme also provides support for orthogonally persistent java.
C++/Java-like interpreter written in C++, using Flex and Bison. Small kernel, user extensions (shared libs) allow to add functions and classes to the system.