I can't get into those "non-game" games like Animal Crossing. It's the simple fun of stuff like Mario Kart that I love Nintendo for.
For anyhting else, I have my PC.
There's already user sites posting "friend lists" so people can know who they are playing. Nintendo discourages this but it's out of there hands as long as the poster is posting his own friend code.
I'll probably pick up a redesigned DS once it comes out. I don't mean a new color, but a redesign. Unless they remove some functionality.
I've seen screens that "unroll" for PC's. Maybe they could design something like that and have the screens be closer together.
You know what would make a good DS game? Scorched Tanks - ONLINE!