client to client communications
 

I'm thinking about writing a simple status monitor addon and was wondering
what techniques are available for sending update information about a status
to another client. What have people done? What works?

The status would not be an in-game value, it would be custom for the
addon. Probably have a simple display on the client side, but what I want
is for the user to select a value, and for other clients to have the ability
to see that value.

The data would likely be small (a simple string or number) so any method
of sharing data would likely work.

I'm not sure this is doable... In my opinion, the only way to share information would be throught the chat log...

The only viable way to share data between seperate clients is to use the messaging system, such as whispers, say-commands, emotes or chat channels.

Many add-ons, when installed, create or join a silent chat channel (a silent channel is one which is not bound to any of your chat frames). Then, the add-on registers for CHAT_MSG_CHANNEL event for itself, and looks at the 'arg9' variable, which contains the channel name. If a channel name match is made, the contents of the message is readed and interpreted, otherwise it's skipped.

If you don't feel like rewriting from scratch, there's always the SkyLight library, a rewrite of the original bloated Sky library. I'm told it works smoothly, but being a naturally suspective person, I'd still implement my own method if I needed to exchange data between clients.

Chat channels
 

It seems like chat channels is the way to go. I've looked at a few other
mods doing this and that seems to be what they use. Maybe I'll
look into a few to see if they'll work the way I want, but chances are
I'll write my own simple tool to do the job.

Thanks for the feedback.