I had an idea to add to the follow, send message, and add friend notifs area. Say you have a friend and you like them, but they love to talk their head off. You can mute certain activity of them. As well as Invite to Group (and can choose which group) and Invite to page (and choose which page) Say for instance you don't want page invites or group invites, you can choose to mute this activity from a friend or friend of a friend.
Group and Page email subscriptions: Send your posts to the group, page or profile newsfeed of your choice, each group or page etc allows for an email address like [email protected] and can mail in a post or picture they see on the web.
Invite friends to groups/pages by email form in each group.
Turn on activity for friends and turn off activity for no longer friended friends. (It won't help to see their posts sometimes)
Send stickers in chat?
Reactions like Facebook and Buddypress?
People you may know Widget for front, members and or your profile page.
Pokes/Other action
Newsfeed location, music track/listening to icon.
On a person's profile have an online now / chat pop up so you can chat with that person