[joegaudet]

IntelliJ has great debugging integration with JS / PHP / Scala (the tools I use currently).

Set a breakpoint in the code, refresh the browser, and all the variables in the scope will be annotated with their value at break time.

This is really what you're after when you're println debugging - it has the advantage of showing you everything in a minimally intrusive way which is helpful when you don't know what you're looking for exactly.

[joegaudet]

If you're doing something like play in scala you usually need the program running in the Intellij context, but it can also hook up to the debugging port of a JVM or to the PHP interpreter running inside of a VM.

IntelliJ is a pretty complete suite of a tools, a pleasure to use (has VIM mode too :P)