This is a decently modularized set of configuration files for a NixOS system, which I mainly use to configure my laptop.
The entrypoint is default.nix, and the module system is used
heavily.
Private files/data are placed in a private subdirectory, which is
hidden via .gitignore.
I place this repository in /etc/nixos, next to my local checkout of
nixpkgs, which I use instead of the channel mechanism. A suitably
modified NIX_PATH allows this to work (see nix.nix).
[anders@gurney:/etc/nixos]
$ ls -la
total 16
drwxr-xr-x 4 root root 4096 Mar 21 22:30 .
drwxr-xr-x 23 root root 4096 Mar 21 22:31 ..
drwxr-xr-x 6 anders users 4096 Mar 21 22:34 configuration
drwxrwxr-x 9 anders users 4096 Mar 21 19:31 nixpkgs
[anders@gurney:/etc/nixos]
$ echo $NIX_PATH
/etc/nixos:nixos-config=/etc/nixos/configuration