On a Linux box, I am building the GNU comiplers and libraries from source (I need to use a third party library, and I am running a couple of year old SuSE Linux distro).

I have played with the GNU gcj Java native compiler before, but (when I get time) I will enjoy experimenting with an up to date version of gcj and the CLASSPATH libraires — certainly is taking a while to build all of the Java libraries!