Simple serial port interfacing?

[laFrog]

I noticed there wasn't much info on this page on serial port stuff.
I'm currently doing a little project where I'm using an old computer as a
"console" box for emulation.

I'm putting in a TV-output graphics card, 1 4-button joystick,
2 original NES controllers on the parallel port, no keyboard or mouse:
the thing boots to a joystick menu that starts (among other things) NES
emulation.
The problem was: I needed another button: for returning to the menu (which is
my own software) Since I didn't want to hack a keyboard and the parallel port
was used, I made a ridiculously simple interface on the serial port:

(DB9)
pin 5 (GND) ----- PC power supply GND
pin 9 (RI) --o/ o--- PC power supply +5V

Switching on/off the Ring Indicator, very simple on the software side too:
buttonstatus = inp(0x3F8 + 6)&0x40;  /* (DOS) */

It seems to work just fine. Has anyone else here given any thought to using
the RS232 like this for squeezing out a few more buttons?
It seems simple enough, and there are more lines that can be used
(e.g. CTS, DSR..)

I was thinking of writing a joystick driver for this kind of interface,
is there any interest? What do you people think?

[SirPoonga]

http://kitsrus.com

Kits 74 and 108\

Maybe they will give you an idea.