BlockNote.net is...uhhh.. an HTML editor. Yes, one could say a competitor to Nvu :-) It's a commercial product. It's really for beginners and it's quite weak but it has a fast rendering/editing engine and a few remarkable UI stuff that need to be quoted as such:

  • the table insertion dialog; I really like it
  • the table manipulation UI; I love it. I am really jealous here, BlockNote.net's author has used a superb metaphor, and I find it better than my inline table editing thingies