Firepad will eventually support rich-text copy/paste and import/export as HTML (export is actually already supported through the API, but not exposed through the existing UI), as well as lists, paragraph indent, and all of the other features that you'd want. They just didn't make it in for the v1 release. :-)

As for similar projects that are already more HTML-friendly, maybe check out Etherpad[1]? It has HTML import / export, though I haven't tested it out.

1. http://etherpad.org/

http://scratchpad.io might be what you're looking for.

We are building a real time HTML synchronization engine at wikidocs.com (using a custom OT engine). It's still work in progress, but you can already try it out - if you fire up the inspector and manipulate the DOM, your changes will be synchronized automatically.

Plunker is a collaborative html/css/js/coffee-script/typescript/less/etc... editor: http://plnkr.co/edit/?p=preview&s=YDQtgmV5y7I6EQfJ