When I first got into the alpha of World of Warcraft I quickly concluded that keyboard commands and hotkeys would not cut it when it came to on-line communication.
My friend here at Stardock who is also on the alpha introduced me to Ventrillo: http://www.ventrilo.com
Ventrillo is a voice chat system. It's like IRC but with voice. I assigned my Ctrl key as the hot key to let me talk. I just have a microphone on my desktop and talk to the other members of my guild. It's a great way of communicating because it's so clear and easy.
You do have to set up a server in order to use Ventrillo -- someone has to relay all that stuff. When the game's released, I'll have a special server just for those who join our guild so that people can easily communicate back and forth to each other.
I highly recommend giving it a try. It's so good that we're thinking about using it here at the office for communicating with our European developers.