Burl is a completely web based HTML and CSS Editor. It supports all the
latest CSS3 styles and HTML5 updates. Its plugin architect makes it very 
easy to develop plugins for as well as a powerful web page creator.
 
Right now Burl, even though it is still in major development, is fairly 
functional.
 
Below is a list of what it can do:
  Handle multiple Users
  Handle multiple projects
  Handle multiple files within projects
  Save Files
  Enable disable Addons and Plugins 
  Multiple Window Support
  Support for Most CSS Styles
  Copy,Paste,Create,Delete Elements
  Have Multiple project open at the same time
 
What We need and are working on:
  Cross Browser CSS Support
  CSS Style Properties
  Class Creation and Removal
  Save Class as style sheets in their own file
  Support for CSS Styles 100%
  Easly create Tables
  Images
  Custom HTML Attributes

Burl is still in development and therefore still has many rough edges
and sharp sticks that need to be dealt with. But still, try it out.
  

From the developer:

I created this application
because of my extreme lack
of visual coordination.
In other words, I could
not design a web site that
I liked. So I created Burl.

It didnt help.
Now, I can design crummy
websites even faster.