I've been struggling with the implmentation of the server-side code that would allow me to exchange peer IDs. Really, I'd just like to know what the most secure, and fastest, coding language would be to use. Would anyone have any good resources I could check out? I'm looking into using PHP, but I'm not very skilled in that language (though I'm not very skilled in much beyond AS3). I'd love to have a solid grip on what I'm doing with that for the sake of my apps moving forward, so any and all help would be greatly appreciated. Thanks guys.
Choice of platform/language is a matter of taste, skill and other constraints.
If you know nothing but AS3 you could distribute ID's via FMS's remote shared objects (no serverside [AS1] scripting needed), although that may turn out to be the most expensive choice.
If you don't mind a few headaches you may use the free Red5.
I wrote a simple java socket server and run this on my VPS.
google for 'flash socket server in five minutes' for a good tutorial