Charter GlassFish Technology Partner Halcyon Monitoring Solutions, Inc. is offering a free eval of its PrimeAlert GlassFish monitoring (which includes monitoring of the GlassFish JVM and MySQL database instances). The service is only $4000/year for customer sites with up to 1000 employees. AND Halcyon has been monitoring Sun infrastructure practically since the dawn of time, so it's a credible solution.
Do check it out at your earliest convenience.