This article referred to both load testers as well as J2EE monitors; this section defines several of the more popular products.
LoadRunner by Mercury Interactive (most popular)
Benchmark Factory by Quest Software
The Grinder (open source)
Unfortunately, there are not any integrated tuners that I am aware of. But...that leads to an open source project that my Microsoft-based programming counterpart and I have created for just that purpose! For all the updates, check http://etf.sourceforge.net. I will demonstrate it in many of the forthcoming application server-specific tuning articles.