Based on an informal scan of the people typing away at their laptops in hallways of the recently held OSCMS, it seemed like 2 out of 3 computers (at least) bore an apple logo. With a user base like this it would be a shame to not centralized some of the knowledge, tips, and/or tools for others to report on and share!

...to this purpose, here's a list of some recommendable tools that can provide a good starting point for anyone who is trying to turn their Mac into a lean and mean development machine:

Tools of the Code

Xcode: Apple's developer tools package. This 900+mb package adds gazillions of system/command line stuff to your system that you'll be needing down the line (e.g., CVS, GCC, and other such things which ). If you are going to be doing serious development you might as well install it - you will certainly run into many dependancies that this takes care of. [free]

SVN: The SVN version which comes with Xcode is more or less ancient. Fortunately, there are a couple of places to get newer svn versions from: 1.0-1.3, and 1.4. [free]

iTerm: iTerm is a replacement for your mac's "Terminal" application. There are other nice features, but the tabbed interface and the bookmark functionality alone makes iTerm a no-brainer for working on the command-line. [free]

FireFox: You gotta have FireFox so that you can: a) test out your sites in it, b) so you can install and use FireBug and the Web Developer plugins. [free]

Firebug: A great, and free, CSS and Javascript troubleshoot and editor. This one's a real sanity/time saver. [dependency: FireFox, cost: free]

FireFox Web Developer Plugin: More page analysis/troubleshooting tools. Indispensable. [dependency: FireFox, cost: free]

TextSoap: Costs a few bucks but it's text cleaning tools are really handy for turning dirty text (e.g., invisible character that will cause parse errors) from web pages, emails, and/or word processing docs into source code. [cost: $29.95, 30 day demo]

Apache, Linux, MySQL

MAMP: MAMP stands for, "Macintosh, Apache, Mysql and PHP". Basically, this is a totally self-contained server environment that is installed and at the click of a button. Definitely the quickest path to getting a localhost up and running, but the fact that MAMP is self-contained means that it doesn't integrate into rest of the OS in the same way, for example, that the built in Apache webserver which comes with your mac does. This may not matter though if you do not anticipate needing to recompile/customize your installations. [free]

Roll your own: Hardcore devs or devs that aren't hardcore, but need functionality/modules/versions that are different than what comes with MAMP will need to roll their own Apache, PHP, MYSQL solution. Fortunately, your mac comes with two of the three ready to go right out of the box. Apache 1.3 comes pre-installed so does PHP 4. You'll just need to adjust your httpd.conf file so that apache works the way you want it to and so that PHP will be loaded when apache is started (it comes disabled by default). Once you get those two on their feet it's just a matter of installing MySQL, and perhaps PHPMyAdmin in order to help you administer your database (note there is also a socket issue that needs to be accounted for when installing MySQL on OS X). [free]

Source/Text Editors

(Generally speaking you should only need one of these, though you may want to try them all out and see what fits you best - and of course, it's worth mentioning that this is by no means an exhaustive list of every editor available for Mac OS X)
TextWrangler: An awesomely powerful and agile text/code editor considering it's price (free).

TextMate: There is a strong TextMate user base within the Drupal community, as evidence by the Drupal TextMate Bundle developed by Steven Wittens. [39 euro]

KomodoEdit: The free, 'lite' version of the Komodo Integrated Development Environment (IDE).

Eclipse: Open source (free), Integrated Development Environment (IDE).

File Transfer

(again, you will likely only need one of these apps so try them and pick your favorite)
RBrowser: It's not free, but this wonderful little GUI-based sftp/ftp client is the only one I know that will let one 'sudo su' [e.g. access with root permission], a feature that should probably be outlawed for how much more it makes a person want to avoid their command-line. [$35 - demo available]

FUGU: A free alternative to RBrowser that is supposed to be decent

Assorted Applications / Utilities

Tinkertool: "TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows you to activate hidden features in the operating system and in some of the applications delivered with the system." - for instance you will be able to see your .htaccess files in the Finder. (free)

WindowShade: Sanity-saver, desktop tool. Allows the minimizing of windows to just the width/height of its title bar by simply clicking the title bar and/or prefered keystroke combo, rather than having the entire window minimized to the dock. ($10 and well worth it)

Desktop Manager: Allows for multiple desktops, screen switching. [free]

Diablotin: A PreferencePane. Diablotin allows you to manage the items that have been added to the Mac OS X Library folders. So this means that you can put you mac on a diet and disable virtually any/alls part(s) of the OS X system architecture and claim some wasted system resources. [free]

EasyFind: For those who are irritated by Mac OS X's inability to easily search any and all files on your hard drive (Tiger by default excludes many system directories and/or files), EasyFind brings back the search functionality/simplicity that mac users were accustomed to before Mac OS 10.4 came out. [free]

Fink: Fink is a whole world unto itself: "The Fink project wants to bring the full world of Unix Open Source software to Darwin and Mac OS X. We modify Unix software so that it compiles and runs on Mac OS X ("port" it) and make it available for download as a coherent distribution. Fink uses Debian tools like dpkg and apt-get to provide powerful binary package management. You can choose whether you want to download pre-compiled binary packages or build everything from source."