What distribution does not support startx out of the box. If you boot into terminal (or kill the X service), then startx should just do whatever the system does to start the X server anyway.
startx from a VT should give you an X server. You can get from there to a standard session (minus the DM) by setting the appropriate environment variables and making sure the right session manager is executed.
I don't call that 'no configuration' though. And if you want to startx into Fluxbox you also have to make sure that all of the aforementioned services are run (unless you're totally abandoning your Desktop environment, in which case this whole conversation is pointless).
In my .profile I have: # if logging into tty6 startx if [ -z "$DISPLAY" ] && [ $(tty) = /dev/tty6 ]; then startx ; fi
Then in my .xinitrc I have xrdb -merge ~/.Xresources eval $(gpg-agent --daemon) exec ck-launch-session dbus-launch awesome
My full desktop environment uses 116MB RAM at boot and everything works flawlessly.