Users can now send messages to their offline friends, making the service more of an enduring chat log. Blizzard Groups aim to be a robust nexus for convos between a set selection of people, supporting multiple text and voice channels (say, for different subgroups playing various games) and tools for Group administrators to manage and invite new members. In other words, like a mini social guild -- or, as Glixel sees it, like Slack. And at long last, you can finally appear 'offline' to sneak some secret game time in.
Players now have a personal profile and avatar to represent them throughout all of Blizzard gamingdom. Its 'About' page has fields for you to list things about you, favorite games, links to personal sites and/or song lyrics, like every good social site (thankfully, you can make your personal info private). Players have over a hundred heroes, villains and characters from Blizzard games to select as their account's avatar.
Lastly, you can also now give in-game gifts through Battle.net to other players. If you want to send a buddy a Hearthstone card pack or Overwatch loot box, choose the 'Gift' option during checkout and select the appropriate player from a drop-down menu (or enter their BattleTag).