Nintendo's WiiSpeak demo was one of the freakiest things that happened during E3. Basically, Nintendo had an Animal Crossing demo running in their conference room, with a WiiSpeak mic connected. In an undisclosed location somewhere else in the convention center, Charles Martinet was also playing City Folk, with a Mario-style avatar, and riffing in the Mario voice with whoever happened to wander by.
Mostly, this entailed yelling at other players for messing with his flowers, and complaining about the lack of bugs nearby. I tried to interact with Mr. Martinet, but the WiiSpeak couldn't pick up my normal speaking voice (which is admittedly mousy and whisper-quiet). As I was walking away, Mario started smacking the other players with his axe.