My Idea for this post is an in-game friends list for Terraria.
How to Add
To add someone, you need to first find them in a server. Type /friendrequest [player name]. On the person you want to add's computer, a message in the text box saying "[Person sending friend request's name] has sent a friend request!"
If you exit to the main menu, there will be a new button saying "Friends." There you can see the Steam name and the player name of people you added/sent friend requests to. Also you can choose who you want to see the IP of the server you're in, who you want to receive messages from, and if people can invite you to a server/join the server you are in.
Please comment if you like and/or have an idea!