I think "locking" villagers is a bad idea. Animal Crossing is supposed to progress like in real life; in real life, you can't force someone to stay in a town. Plus, it'll make the gameplay stale.
Also, if a villager isn't close friends with you or you have been mean to the villager and wishes to move out, they won't tell you that they're moving out. You can only find out by hearing rumours from other villagers.
There's a telephone in the attic (like AC:CF) which you can use to call villagers. You can ask them to come to your town using the telephone. Your friendship level will decrease if you hang up on them too much. Villagers will generally be annoyed if you call them late at night or early in the morning.
You can wake up sleeping villagers by making too much noise outside their homes (by repeatedly smacking a shovel against the building, or using the megaphone right next to their house). They are likely to be annoyed if you do this.
There will be a city which is an online AC chatroom. 15 people can enter one chatroom, and if someone gets a wifi error, only they will be disconnected from the game, not everyone else.
- - - Post Merge - - -
we had them in city folk, not sure why they got rid of them :<
I know right? I used to feel like a sophisticated grown-up when I was a young(er) kid running about in the city and buying GracieGrace clothing. ;-;