I don't know if this already exists; I've searched through the forums and the wiki, but I may have missed something.
Anyway, what I would have liked to find, is a "walkthrough" of which config files and such are accessed during bootup, and in which order; which central files invoke which others, which lines in the boot scripts call on which config files to be executed, etc. I know, it can probably be pieced together by going through all the files in /etc, but it would be nice to have it set up in one place.
It doesn't necessarily have to be absolutely complete, with all the possible alternatives for any module, but at least the Arch-essential thread of files, with indications of where extra stuff would come in (X?, modules?, daemons, etc.)
The first file is the /boot/grub/menu.lst when it comes to the decision which OS to boot.
is the central file in arch: It loads your locales, modules, network settings, daemons
defines your typical working mode (5 for X-session)
is what your login-manager (xdm/slim/whatever) relies on when he has to start your your windowmanager/desktop environment, afaik kdm automatically detects which Windowmanagers/Desktop Environments are installed, with gdm: no idea, never used it
quite new but also important in my opinion is
which defines what to be included in the init ramdisk, but I would net recommend you to play with it until you really know what to do (the wiki tells you more)
I hope, i forgot nothing important...
things like the /etc/fstab should be clear, i hope!
a happy archer hellwoofa