Being a Mac user since 4 years this is my selection of softwares that i’m using every day on my job as a web developer :
The best IDE (for me) to develop web applications with Xdebug integration, simple template insertion,project library parsing and many other stuffs, however Netbeans could be an alternative but it’s still having memory allocations problems (see Netbeans Forum).
Sequel Pro (free)
MySQL database management for MacOS, simply the best!
Navicat Lite is a multi-connections Database Administration tool allowing you to connect to MySQL, PostgreSQL and Oracle databases simultaneously within a single application
FTP, SFTP, WebDAV, Cloud Files, Google Docs & S3 Browser for Mac & Windows.
Access Unix basis of Mac Os, useful for creating / searching content, files, SSH, FTP commands etc.
Soap Client (free)
SOAP Client is a free Cocoa-based developer tool for Mac OS X Tiger that allows you access and debug WSDL & SOAP-based Web Services from the comfort of your desktop.
MySQL Workbench (free)
MySQL Workbench is a cross-platform, visual database design tool developed by MySQL. It is the highly anticipated successor application of the DBDesigner4 project. MySQL Workbench is available as a native GUI tool on Windows, Linux and OS X in different editions. See the following link for more information about the editions available.