Well, relays are one of the  pillars of Nostr. Clients (or what most people call “apps”) are another part of it.

But you’re generally right. You can have a private relay that only stores your notes as a backup and does not rebroadcast anything. You can have a read-only relay that fetches info from rss feeds or Mastodon or other sources outside of Nostr and broadcasts it to Nostr users. There are many more options, virtually limited by your imagination only.

And yes, there are tons of “Apps” out there. 

The main thing to realize is Nostr is a communications protocol, not an app. It can be used to exchange any kind of information. 

I’ve written a series of posts called “A Million Tiny Worlds”. I urge you to have a look. 

https://habla.news/tony/productivity

https://habla.news/tony/multimedia

https://habla.news/tony/stats-and-data