For vim there is a filesystem explorer called NERDtree: https://github.com/scrooloose/nerdtree
Surely an alternative or superior package exists for Emacs?
Personally, I prefer the ECB's tree mode. http://ecb.sourceforge.net/
You should also check out the CEDET stuff. http://cedet.sourceforge.net/ They contain a lot of other useful stuff that you can use for similar development needs.