Honestly, a single thread might be a decent idea. If you were interested in collaborating on an ATM idea, you could send a PM to a mod/admin and inform them of such. The mod could then unlock the thread, post your interest and mod-approved synopsis (as discussed above), and relock the thread. This would enforce "no promotion" on several levels. People who were willing to collaborate on others' ATM ideas could keep an eye on that thread, which could be a clearinghouse. Easier for people willing to collaborate than seeking out anyone whose sig line indicated their ATM idea. Easier to police for the mods. And if you, the ATM proponent, had a specific person in mind, you could always send that person a PM, though I would imagine that would get fairly tedious for certain people. I suspect certain members would get approached relatively regularly, whether they're interested or not.
"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"
"You can't erase icing."
"I can't believe it doesn't work! I found it on the internet, man!"