Hi DrFran,
If you are talking about the typing in the air animation, that one can easily be switched off:
Go to preferences (CTRL P) - Chat - and uncheck "playing typing animation" (I'm on a german language version of the viewer so I don't know the exact wording ;-)
Now the avatars won't type anymore while talking
If you're looking for better animations to replace the standard typing, a number of shops sell those animations which are to be put into an animation overrider. Each of your avatars would need one with the appropriate animation(s) loaded.
I hope that helps a bit - have fun doing machinima ;-)