Post ideas you’d like to see become businesses, pain points you’d like solved, etc. but you don’t have time to pursue.
Social networks have the problem of people using one account for everything they want to talk about, but often you are only interested in part of their lives. Keyword/hashtag muting doesn’t do a good job.
A solution: a social network where, instead of having a Tweet or Post button, have two or more buttons, such as Personal, Professional, and Political so posts are automatically tagged and can be muted/unmuted en mass for that user. I.e. user writes a post and then has to choose if the post is personal OR professional OR whatever, and can only press one button to post. Have some logic to prevent people posting the same text under more than one tag without deleting the old post. Perhaps have a couple fixed buttons and a couple buttons which are configurable, so people could make a Sports button or the like to auto tag sports posts. Charge people each time they customize a button (and monetize the network in other ways, of course).