Just reading the various posts about using healbot or grid for healing (similar to clickboxer i think), and wanting to do it myself. I wonder if something like the following exists or could be possible (and legit) to create.
An addon that would take a button click from within your mains (presumably the tank) window like grid/healbot, but then used the in game chat functions (either via whisper or hidden chat channel) to send commands to the healer window. the healer window would receive the command and set off a /cast depending on the command that it receives (eg. code sent="./cast [target=tankname] Riptide" then the healer side addon simly removes the "." and runs it like an addon). I've seen Jamba relay whispers, and the wintertimer addon makes use of a hidden chat channel to communicate times, created wintergrasp raid available, etc between the players with the addon running.
Potentially it could be used not just for healing, but for things like hearthstones, buffs, etc, and in doing so freeing up keyboard binds for various other in combat, speed reliant functions.
Is this an idea that is already in play somewhere? could be done in a legit way? or am I way off the mark here?
I'd try myself, but I have yet to dive into the world off addon programming.

PS. I was on these forums awhile ago, but dropped multiboxing for awhile in favor of running my main 80 through ulduar content with one of the top guilds on my server. looking at starting boxing again at a slower pace.