Sleepycat Software has posted the first public beta of Berkeley DB Java edition. Berkeley DB JE is a non-relational embedded database written in Java. The data is exposed through "a Java Collections-style interface, as well as a programmatic interface similar to the Berkeley DB API." As near as I can make out, this is payware, but open source products can get a free license if they want to integrate it into their own programs. Java 1.4.2 or later is required.
Michael Koch has posted the GCJ web browser plugin 0.2.2. This free-as-in-speech (GPL) plug-in execute Java applets in Mozilla 1.7 and compatible browsers using the GCJ virtual machine.