Thanks everyone who responded to my question!

I did a poor job of delineating the restrictions I face in this task:

1. I want to send small bursts of data at a highish rate, say one byte
every AC cycle or so at 9600bps, so that the data transfer aspect of the
indicator is invisible.

2. I want to use the built-in RS232 drivers in my C compiler, for
simplicity.  This eliminates the internally generated carrier freq as an
option.

3. I don't want to add any hardware costs, such as a modulator for a
carrier freq.

4. A red indicator is fine.

5. The detector can be placed right over the indicator, sheilding all
ambient light.

So far:
I can do 9600bps through an IR led and photodiode, without an amplifier at
all.  But I have have not had any luck using any kind of red LED with an IR
detector, or with any of the visible-light transistors I have found, or
with the transistor's colector-base junction, with or without an amplifier.

I will look around for integrated devices per some suggestions, but:

Digikey doesn't sell any Motorola; did you mean the Photonoc Detectors
parts, Andy?

PIN diodes don't seem sensitive enough around 700nm (standard red).

Thanks all!

Bruce Cannon