There are lots of great special purpose extensions for your favourite
language in Emacs (e.g. I use emacs-eclim for Java), but there's a
small gem called imenu which gives you a lot of this for free
without any setup of any can.
It scans the source code in your buffer and provides these in a
menu. Combining this with a completion like helm-imenu, you have a
really neat simple code navigation for any source file you open. No
setup required.
For the time being, I prefer using vanilla imenu together with
ido-ubiquitous and ido-vertical-mode over helm-imenu as ido
gives a faster experience and it doesn't alter my UI too much.
I've bound imenu to Ctrl+,:
(global-set-key (kbd "C-,") 'imenu)
Happy hacking.
