I want the various workout emotes I see NPCs doing (squad in GC barracks, random soldiers training, ect). Those are already in the game so it would be trivial for SE to give us!

Peace sign, raspberry, and bunny ears would be great!

I want any and all new dances.

Paired emote (like couples dance already mentioned) would be amazing. They'd need a mechanism to synch it though, since the game's high latency kills attempts to actually time things. Seriously, give it a try with someone playing the game next to you sometime. Even with <100ms ping, there is about a second delay to actually get something processed on the server. The game's true latency is much higher than the ping you get. If you timed it, you could get it right on your screen, but it would be wrong for everyone else.

Uldah's dance party on little ladie's day looked synced because the mass of player dance animations all started the moment you entered the map.