Seeking Good DHTML Debuggers?

christodd queries: "After years of programming in PHP and C++, I've finally delved into the world of Javascript and DHTML. The biggest hurdle I have come up against is the various web browser DOMs. I find that I spend much time googling for variable names, and guessing which variables do what. My favorite tool is a good debugger, and this is where I'm having problems. There is a commercial product by Netscript due out this quarter for $190.00, and there is a very young open source project at BiteSizeInc, but I have yet to find anything production quality. How does everyone else debug browser DOM issues?"