A debugger is not only something a developer uses to hunt for bugs. It is also a tool that makes a developer more productive.
In Smalltalk the debugging experience is really impressive. As someone once said:
"I love Smalltalk. I love coding in the debugger, being able to archive processes and restore them exactly later if they encounter exceptions, the amazing reliability. The economy of expression and the brilliant class library."
Soon Amber Smalltalk will bring this debugging experience also to web development. Have a look at this demo video.