Today I found a good AJAX editor for Mac OS; This is not only for Mac.
The name is Komodo. ActiveState company made it: http://activestate.com
The company has made many editors, but among them "Komodo Editor" is free and open-source.
I has special function for many AJAX tool kits such as Dojo, Ext, and YUI.
I though it must be commercial, but the official web site announced it is totally free.