GCJ, the GNU Compiler for Java, has been languishing for some time, and
may be about to be put out of its misery.
Unlike the Sun/Oracle compiler, GCJ can compile to native machine code
(thanks to the common GCC infrastructure), it is not restricted to some
intermediate byte code. It originated before Sun open-sourced Java, and
I guess a lot of the need for it went away when OpenJDK appeared.