Multiple OS

• ActiveState Komodo Edit
• Aptana - Supports FTP and SFTP (Only version <= 1.5)
• Eclipse - PHPEclipse and PHP Development Tools projects. With additional plugins supports SVN, CVS, Database modelling, SSH/FTP access, Database Navigation, Trac integration, and others.
• Emacs - Advanced text editor. The nXhtml addon has special support for PHP (and other template languages).
• Geany
• jEdit - Versatile Free/Open source editor. Supports SFTP and FTP.
• nano
• Netbeans IDE - A dedicated PHP coding environment and complete integration with web standards. Supports SFTP and FTP.
• pico
• Vim - provides PHP syntax highlighting.
• SciTE - fast, PHP syntax highlighting, compiler integration, powerful config via Lua API:LUA
  

Windows

• Alleycode HTML Editor - Freeware editor with syntax highlighting for both php and html.
• ConTEXT - Freeware editor with syntax highlighting.
• CodeLobster
• Crimson Editor - Lightweight editor. Supports FTP.
• Dev-PHP IDE
• DzSoft PHP Editor
• Eclipse
• HTML-Kit - Syntax highlighting, Supports FTP.
• Netbeans IDE - A dedicated PHP coding environment and complete integration with web standards. Supports SFTP and FTP.
• Notepad++ - Supports FTP and is maintained very well.
• PHPEdit - Free for non commercial use, shareware, counts down from 30 days after install.
• Programmer's Notepad
• PSPad - Supports FTP.
• Microsoft Office SharePoint Designer - Now a free download from Microsoft (no syntax coloring or auto-complete for PHP).
• EditPlus - Free for non commercial use, shareware, counts down from 30 days after install.

Linux

• Bluefish - Supports any protocol that is supported by GnomeVFS. (SSH...)
• Geany
• gedit
• gPHPEdit
• Kwrite
• Kate - Supports any protocol that is supported by KDE. (FTP, SSH...)
• KDevelop - Supports any protocol that is supported by KDE. (FTP, SSH...)
• Netbeans IDE - A dedicated PHP coding environment and complete integration with web standards. Supports SFTP and FTP.
• Quanta Plus - Supports any protocol that is supported by KDE. (FTP, SSH...)

Mac OS X

• Smultron
• TextWrangler - Supports SFTP and FTP

Commercial editors

• Adobe Dreamweaver - Supports SFTP and FTP
• BBEdit - Supports FTP
• Coda - OSX
• Espresso - OSX
• Code Crusader IDE - Trial available
• Delphi for PHP
• EditPlus - Supports SFTP and FTP; Trial available
• EmEditor
• JetBrains Web IDE - professional PHP IDE with advanced editor and other web development specific tools. Currently in Early Access (EAP)
• Microsoft Expression Web - Full PHP support with syntax highlighting, etc; Trial available
• PHPEdit - Supports SFTP and FTP
• phpDesigner - Supports SFTP and FTP, syntax highlighting for many programming languages; Trial available
• skEdit
• SlickEdit
• TextMate - Trial available
• TextPad - Trial available
• Top PHP Studio - Supports FTP
• UltraEdit - Supports SFTP and FTP; Trial Available
• Zend Studio - Supports SFTP and FTP (Eclipse with Zend's Commercial Plug-in)
• PHPEd - Supports FTP, SFTP and WebDav