MechanisM

I think that Telegram is more like 3rd one.. It has nice desktop apps and group chats with bots like jaconda.im Dunno about other messengers, but Telegram offers channels! And this is awesome! + nice options to share with telegram via some links

Twitter Bootstrap enabled editor http://jhollingworth.github.com/bootstrap-wysihtml5/

This is another one russian text editor - http://elrte.org/demo. Comes with filemanager - http://elfinder.org/

Take a look at http://jejacks0n.github.com/mercury/

It's good but codebase is so huge..