The Grinder is a good free load-testing tool and it is used extensively in J2EE Performance Testing with BEA WebLogic Server, this week's book promotion. [ October 16, 2002: Message edited by: Chris Mathews ]
There is also Precise'sIndepth for J2EE. A very ncie tool, but it does cost some $$$. Later.
<a href="http://www.tangosol.com" target="_blank" rel="nofollow">www.tangosol.com</a><br /><a href="http://www.tangosol.com/coherence.jsp" target="_blank" rel="nofollow">Coherence:</a> Easily share live data across a cluster!