Sure! There are many scripts that provide such capability, and Dreamhost’s own net2ftp installation (http://webftp.dreamhost.com) has that capability. You don’t want to use the DH net2ftp to edit perl or system files (line ending issues) but it should be fine for php/html files.
Actually, I like ffileman for such tasks as it is easy to install, versatile, and highly functional. There are also many other such products available (check hotscripts.com), so you should be able to easily find something that meets your needs.
I do recommend that you avoid the “WYSIWYG” editors if you are going to be working with PHP files, and they all have their shortcomings when it comes to flexibility with html files.