I've been looking at SLAMD lately - http://www.slamd.com/ http://www.slamd.com/. It's also distributed and can be controlled largely by a built in web interface

I've been looking at SLAMD lately - http://www.slamd.com/ http://www.slamd.com/. It's also distributed and can be controlled largely by a built in web interface. With many of the other distributed tools (JMeter, The Grinder) you have to muck around with the Java desktop app which is less than intuitive.