Excelsior JET (http://www.excelsior-usa.com/jet.html) is a complete
Java SE 6 implementation enhanced with an Ahead-Of-Time (AOT)
compiler. It is certified Java Compatible on a number of Windows and
Linux platforms, including Windows Vista and RHEL 5.

http://www.excelsior-usa.com/jetlatest.html provides full information
on new features and improvements.

http://www.excelsior-usa.com/jetdleval.html has free trial downloads
available (registration is optional.)

http://www.excelsior-usa.com/jetfree.html offers a free license
to authors of non-commercial Java software.