You need to share notes with @Josiah who is working on a bookmarks system at the moment!

To delete you can tag a post as deleted even though the data itself is immutable - as long as the client knows how to handle it when it comes to rendering, it doesn't really matter.

That sounds fantastic and useful.

I was thinking of an altnet so that nobody but you has to host the data. Although obviously if you want to optionally make bookmarks public it makes much more sense to have that on the main net.