There are plenty of interesting 
   articles written about Mac OS X application for switchers, but I have to see a 
   guide focused on programmers switching from other operating systems. I hope 
   this article will help you find some cool tools, which may help you with 
   programming.   
   1) 
    Xcode2 (Free – Intel/PPC)
   As the 
    Apple Developer Connection website describes, Xcode 2.3 is the fastest 
   and easiest way for developers to create applications for Mac OS X Tiger. It's 
   also the best way to take advantage of all of the new developer technologies 
   that Apple has put into Tiger. Xcode brings together the power of UNIX, a mix 
   of high-performance development technologies, and the ease of use of Mac OS X. 
   Whether you're writing your application in C, C++, Objective-C, or Java, 
   scripting in AppleScript, or looking to migrate code from another legacy tool, 
   you'll find that Xcode is the perfect tool.   
   The latest Xcode version can be downloaded (for free) from the Apple Developer 
   Connection but free registration is a prerequisite. The complete disk image is 
   around 915MB and if you have a fast Internet connection, it won’t take too long 
   to download. If not, you can also find a copy in you Apple installation DVD.   
   2) 
TextMate    ($39 – Intel/PPC)
   In my opinion this is probably the best text editor for Macs. Although it 
   carries a higher price tag, you are sure that the money well spent. You can 
   open entire directories with a single command and have the whole project open 
   at once. According to its developer Created by a closet UNIX geek who was lured 
   to the Mac platform by its ease of use and elegance, TextMate has been referred 
   to as the culmination of Emacs and OS X and has resulted in countless requests 
   for both a Windows and Linux port, but TextMate remains exclusive for the Mac, 
   and that is how we like it!   
   TextMate is not an IDE but by using its powerful snippets, macros, and unique 
   scoping system, it can often provide features that even a language specific IDE 
   lacks. It has enough project management features to keep most users happy, but 
   is otherwise kept lightweight with a clean and minimalistic GUI.   
   If you are looking for a free text editor, I would strongly suggest you to 
   check 
VI/VIM   out. You may feel uncomfortable in the beginning to accustom to use it but once 
   you know the basics it is fun to work with.   
   3) 
    iTerm (Free – Beta only)
   I use the Terminal quite often for executing Bash code or installing binaries. 
   I was happy using default Terminal provided by Apple until I found iTerm. For 
   me it is a simple but an elegant piece of software. What I like most about 
   iTerm is the “Tab” funtion. Instead of opening couple of windows, you can just 
   work on one widow and switch to any Tab you want. Here is what iTerm developers 
   have to say.   
   iTerm is a full featured terminal emulation program written for OS X using 
   Cocoa. We are aiming at providing users with best command line experience under 
   OS X. The letter i represents a native Apple look and feel of the program 
   interface, and an emphasis on complete international support. iTerm was merged 
   from two projects, CTerminal and TerminalX, both of which were based on 
   JTerminal project. The current version is still in beta stage. It is however 
   very much functional and usable.      
   4) 
MAMP   (Free – Intel/PPC)
   Whether you are a hobby web designer or a professional developer, MAMP comes in 
   handy when you need to test your product. The abbreviation MAMP stands for: 
   Macintosh, Apache, Mysql and PHP. With just a few mouse-clicks, you can install 
   Apache, PHP and MySQL for Mac OS X!   
   MAMP is installed in the typical Mac fashion: very easily. MAMP will not 
   compromise any existing Apache installation already running with your OS X. You 
   can install Apache, PHP and MySQL without starting a script or having to change 
   any configuration files. However the developers do not recommend using it as a 
   Live webserver.   
   5) 
NVU (Free – 
   PPC only)
   NVU was originally developed for Linux but now it is also available for Windows 
   and OS X. It is a complete web authoring system, which could even compete with 
   Dreamweaver. Some of the highlights are the WYSIWYG editor, integrated FTP 
   capabilities and Tab editing.   
   6) 
Tramsmit   ($17.95 – Intel/PPC)
   Transmit is a very Mac-like FTP / SFTP client. The main features include column 
   view, tabs, a sidebar, new favorites, search, dock status, spring-loaded 
   folders, iDisk and WebDAV support.   
   If you are looking for a free application I would highly recommend you to try 
   Cyberduck, which has pretty much the same features and also available for both 
   Intel and PPC based Macs.   
   7) 
    Zend Studio ($ 99 – PPC only)
   Zend Studio 5 is the only Integrated Development Environment (IDE) available 
   for professional developers that encompass all the development components 
   necessary for the full PHP application lifecycle. Through a comprehensive set 
   of editing, debugging, analysis, optimization and database tools, Zend Studio 5 
   speeds development cycles and simplifies complex projects.   
   8) 
Parallels   ($ 49.99 – Intel only)
   Although it is not directly related to Developer tools, it you are developing 
   cross platform applications, this would be a good choice. Parallels Desktop for 
   Mac is the first solution that gives Apple users the ability to run Windows, 
   Linux or any other operating system and their critical applications at the same 
   time as Mac OS X on any Intel-powered iMac, Mac Mini, MacBook or MacBook Pro.   
   Unlike dual-boot solutions, in which users must completely shut down Mac OS X 
   and endure a full OS start-up cycle to access a important application, 
   Parallels Desktop for Mac empowers users with the ability to run important 
   Windows programs like Outlook, Access, Internet Explorer and all other 
   applications without having to give up the usability and functionality of their 
   Mac OS X machine even for a few minutes.   
   9) 
CSSEdit   ($24.99 – Intel/PPC)
   CSSEdit features full-blown source editing for the advanced user. With one 
   click you transform the easy to use visual editors into a mighty source code 
   environment.   
   Besides standard coding features such as syntax coloring, find and replace, go 
   to line and auto-indentation, CSSEdit offers intelligent auto-complete. It will 
   never suggest double properties, is fully context sensitive, and remembers the 
   items you use most. The superior organizing capabilities in CSSEdit will make 
   managing your style sheets much easier.   
   10) 
X11   (Free – Intel/PPC)
   The X Window System (more commonly called X11) on Mac OS X provides significant 
   opportunities for Mac OS X developers. Based on the open source XFree86 
   project, X11 for Mac OS X is compatible, fast, and fully integrated with Mac OS 
   X. It includes the full X11R6.6 technology including an X11 window server, 
   Quartz window manager, libraries, and basic utilities such as xterm. Whether a 
   Unix user or an X11 developer (or both), Mac OS X offers a platform where your 
   applications can run without modification. On a Mac, any of the thousands of 
   available X11 applications can run in a window running concurrently alongside 
   iTunes, Microsoft Excel, and any other Cocoa, Carbon, or Java applications.   
   The Applications listed above are some of the very few tools for developers 
   coding on OS X. I have chosen them because they are some of the most commonly 
   used Apps. by thousands of developers around the world. Please aware that, I 
   have extracted some of the text from the respective Developer websites for 
   clarity. If you have more suggestions, do not forget to mention here for the 
   benefit of others.      
   After publishing this article there was a public out cry about not listing huge 
   number of other Applications. As you can imagine the number of potential 
   Applications can be counted in hundreds and it is not possible to add them all 
   here.   
   However I thought it is worth mention about couple of software which I have 
   carelessly ignored but well deserved a mention.      
Eclipse (Free 
   – Intel/PPC)
   This is probably the best integrated development environment for Java. The 
   Eclipse Platform is written in the Java language and comes with extensive 
   plug-in construction toolkits and examples. It has already been deployed on a 
   range of development workstations including Linux, HP-UX, AIX, Solaris, QNX, 
   Mac OS X and Windows based systems.