Used JMeter about 2 weeks ago here. It's pretty cool. Mainly for load testing. It's a little buggy tho, and didn't always process as many requests as we defined. Nowhere near as nice as the commercial tools out there for load testing (LoadRunner, etc), but it's free and does a decent job.
The online documentation is lacking, tho. Although the internal Help file is pretty good.
Haven't used HttpUnit or even JUnit, actually. Just seems like a lot of work to write unit tests for every method and jsp.. :/
yeah, I just got a test working for JMeter in like two minutes. that's pretty cool.
You don't 'have' to write a test for every single method and jsp if you use JUnit.
Thing is, I need something that will handle JavaScript correctly, not just a pre-defined post or get. and it seems that HttpUnit handles this nicely with Mozilla's Rhino (JavaScript for Java). that's cool. I'm still looking into it though....