Very few. Perhaps the best one at the moment is nvu
. It can draw some tables and stuff. But it's not that great yet, but I suggest you to try it out
. A little off the question, but there's also flash for Linux, called f4l
, but also not that great yet.
I've seem at Frank's Corner
that it's possible to get both Dreamweaver and Flash MX running with wine
also seems to be giving some support for Dreamweaver, but I've never tried it.
Now, if you are willing to learn html, I'd recommend you HTML Goodies
. It's much easier then you think and they have plenty of good tutorials in there. Any text editor and a browser will do. There're plenty of html editors for Linux which provides even syntax auto-completitions and previewing such as Quanta Plus
Good luck mate!