I have found an excellent VISUAL CSS designer that you can actually see what will happen with the text that you are formatting.
It is called True Html Editor and can be found here in Opera Widgets.
Note that you must use Opera to run this It includes a button for W3C Validation.

I think that this will be helpful because you don't need to reload the browser every time you want to see a change in your CSS file or XHTML document. Unless you use a program compatible with server-side document editing, this little widget is an excellent tool.

Check it out, it has over 47 000 downloads already!

That's pretty awesome, didn't know you could do that with the widgets in opera. I'll definately be using this because it's small and gets the job done. Other editors can take a while to start up and use alot more resources but if you need the functionality then you will need to get something better than this widget. That doesn't mean it's bad though if you need the html editing then there you go

-HellFire

Good to know someone with that names is using Opera. Already got it.

Nice Widget for Opera, as I am also an Opera user, I didn't really look into those widgets, didn't even thought that they can do such things, when I first tried them.. For such things I were using Edit CSS on Firefox and Web Developer, to see how CSS changes in real time, very comfortable.. but this widget lacks, or maybe I just didn't found how to change it, is the example field is to small..

The example field is quite small, but it does get the job done.
The Web Developer Toolbar in Firefox is an essential for live CSS editing of pages (with the use of DOM of course), very efficient in seeing which selectors you can delete to make the file smaller.
I don't use the widget much, because I have can do server-side file editing with HTML-Kit. Save = upload there. I don't like it though because I get too lazy to back up anything.

I use all of the popular browsers (including some lesser-known ones), don't be fooled by my name