Free group messaging. It's like a private chat room for your small group. Have as many as you want, and it's always free. Now, you can coordinate with coworkers, organize a game night, and keep in touch with family all in the same place.
Contrary to what you might think (or have been told), leaving your phone or laptop plugged in all the time is not bad for its battery. That's because your gadgets, the batteries in them, and the chargers you attach them to are actually pretty smart about the way they do business.
There's no difference in the quality of the charge, or the life of your battery. An iPhone charger, like any other smartphone, tablet, or laptop charger, isn't really a charger at all. It's just a power supply. The charger is in the phone itself -- that's the circuit that decides how to charge the battery, and that's the part that affects battery life. About the only difference between these chargers is how much current they can supply.