Various IDE's provide 'code' browsers that show some sort of overview of modules, packages and methods.

I use Active State's Komodo which shows a tree including the contents of any open files with information pertaining to 'Uses and Requires', Variables, Packages and members indicated with different icons in a cascade that reflects nesting. Double clicking on a node in the tree shifts focus to the appropriate element in the code. Such facilities are pretty common in IDEs generally.