CrimsonCuttle
Skeletron Prime
It would be nice to not have to rely on an Internet connection to connect to other players, as cellular data is normally not good enough for multiplayer videogaming and public WiFi is unreliable. I know that this is possible, as there are several multiplayer smartphone games out there already using such connection methods, and other consoles (e.g. Nintendo's DS line of products) utilizes such connection as well.