Ideas for apps

Inspired by Li.st. If these apps already exists put me on.
  1. Web
    A word webbing app. Good for idea mapping. For work and personal use.
  2. Knock knock
    Joke app for only knock knock jokes. I imagine it having a requesting system where someone knocks on your inbox and the joke progresses from there.
  3. Three word story
    Users are put into random groups. Each group member takes a turn contributing 3 words to a communal story.
  4. Book club
    Like a group chat for readers
  5. A word a day
    App collects a word from you each day. A list is generated every year for you to look at and try to remember why you downloaded this app