I remember Visual Studio had a very cool feature -
as I was stepping through the code, the Variables view was dynamically sorting the variables at the top to be those which are going to change in the next step.

It went further - not only it shown variables, but also expressions.
So if there was
  char* foo[] = ...;
  i = 5;
  foo[i++] = "Hi there";

then the Variables view would show
  foo[i]     null
  i          5
and after stepping over
  foo[i]     "Hi there"
  i          6

That is what I miss most in NetBeans' debugging. It would save plenty of time spent clicking through huge maps, lists, or complex classes.

Thanks for considering,
Ondra