Dreamweaver CS4 is pretty sweet...
For developers Dreamweaver CS4 is pretty sweet, it can do color-coding for Javascript and PHP and can do code completion for many JavaScript libraries such as JQuery, ExtJS, Spry framework and many more.
If you're looking for something free, then try out Aptana for Eclipse, it handles JavaScript and PHP fairly well, but doesn't have a visual development environment like Dreamweaver.
-Eric
Generate DIV's instead of tables...
If you like to design visually and have an app break the content up for you, then you might want to try Softpress Freeway 5 Pro.
Quoted from their website:
REAL CSS CONTROL
Freeway 5 Pro can be used to create CSS (table-less) page layouts using absolute positioning, and exposes the real power of CSS through relative positioning, percentage scaling of all elements, partial styles, and more, and all with the legendary Freeway WYSIWYG design view.