The arguments against WYSIWYG editors for writing papers and reports apply (if anything, stronger) for creating web pages. I'd recommend a text editor with compiler support; just tell it to use gnome-moz-remote (or equivalent) as the compiler. Personally, though, I use a text editor, m4, and make.
But you asked what would do it, not whether it's a bad approach, so... MS Word can save as html; probably OOo, too. Google seems to know of more...
Thanks everyone, but WYSIWYG isn't exactly what i'm looking for.
Since her work is mostly low-level, it is expected that her code would be simple, hand-typed. as an example, MSword generates a complex code, something that is hard to understand simply by looking at it.
I don't mind typing the code, but I would like to see the result simultaneously, so I can quickly spot mistakes.