You can invite your friends to your own town by opening your gates at the station. This will allow up to three of your friends to visit your town and see what you’ve done as mayor.
Naturally, you can also use the station to visit your friends’ towns instead of inviting them to your town.
Speak to the porter next to the gates to visit other towns or invite friends to your town. He will give you a choice between nearby towns and faraway towns. These refer to using local wireless and internet wireless respectively.
There is a locker in the train station, which can be used to access your stored items. This acts like the chests in early Resident Evil games as whatever you put in there is accessible in your friends’ towns as well (and even cupboards in your house).
Using your lockers is a great way to maximise the number of turnips you bring to sell in your friends’ towns when their Re-Tail is buying them at a high price.