Emacs Tag Magic

Tim Bray on programming in C using Emacs...

I’ve been using Emacs, and I seem to recall that it has all sorts of navigation magic.

That would be the "tags" mechanism. Tags work with non-emacs tools as well, but emacs is especially good with them. See the manual.

Tag databases can be created for all kinds of languages.

Those IDE's still have *nothing* on emacs. :-D