Here's my personal dotfile configuration. It's designed to be very easy to extend and modify.
In essence, each directory is a Python module (with excpetion to the "lib" folder).
Each module defines a class that extends from dotfiles.Module, and optionally overrides the install and post_install methods.
To add a module, just make a new directory and add your __init__.py file that defines a class that subclasses dotfiles.Module. Insert any relevants files to that module (config files, settings, etc) inside the directory.
Two class level variables, default_dest and overriden_dests, are used to determine where the files within the module are to be symlinked.
install is called before files are copied over, whereas post_install is called after the install method is executed and all of the module's files are copied.
By default, files are copied into default_dest. You can change the output directory and/or name of certain files by adding them to the overriden_dests dictionary.
Take a look around at "vim" folder to get a general idea of how things work.