Starsiege: Tribes (or maybe it was just the Renegades mod for it, I can't remember) had a really cool voice command system, where instead of pushing, say "T" for Talk or "Y" for Teamchat, you pushed "V" for voice command menu.
This would bring up a voice command menu, organized by topic. "B" would be base, "F" would be flag, "D" defense, "X" for destroy/exterminate, "A" attack, etc.
Pressing "A", for instance, would bring up a list of things to attack, such as "B" for base, or "T" for turrets, and etc.
Thus, to say, "Attack their turrets", you'd press V-A-T (voice menu-attack menu-attack turrets). "Defend the base" would be V-D-B (voice menu-defend menu-defend base). "Destroy their spawns" would be V-X-S (voice menu-destroy menu-destroy spawnpoints). After a while it becomes really intuitive.
You'd have to press three keys to say something, but you have to press FOUR keys just to say brb (be right back) or igi (I'm going in) or omw (on my way) anyway, since you have to press "T" for Talk, as it is now.
Also, a lot of Tribes players used short acronyms for such simple statements (like brt for be right there or gtf for get their flag) so many already were familiar with three-letter combinations (dob = defend our base, dtb = destroy their base).
Anyway it worked really cool, kept you from getting sniped while typing, and cut down on the "why won't anybody listen/act like a team/take orders from me?" chatter. Plus it was a lot of fun, and way more useful than a bunch of stupid "learn to aim/you suck/try again" UT-type jack@$$ taunts.
The final point would be to bind the taunts and simple statements to submenu "V", so pressing V-V-C would be for the existing "C'mon", V-V-G would be "Grenade!", V-V-V would be "Listen up!", V-V-X would be "Destroy them all!", and etc. This system works really well. And you might even be able to find the existing menus, somewhere in cyberland.
Oh, and as noted above, spamming should be made impossible (in Tribes you couldn't talk for a certain length of time if you clogged up the channel). Also, motormouths usually got kicked or TK'd, teams could nominate and elect leaders, and Teamchat was in green, Enemychat was in red and Allchat was in yellow (to the best of my limited recollection).
Does anybody else remember this?
PlayerOne
P.S. Please note that this is a voice COMMAND system, to facilitate teamplay, as opposed to a strictly voice TAUNT system, to p!$$ off your enemies (although that might help you win, too). Alien voices should sound alien, battlesuit voice should sound metallic, players on top of the stats should have very authorative voices, players with low stats should have tiny voices, builders should have background noise or interference (as noted above). Just my two cents. V-O-A = Order Acknowledged.