Basic Applications and Utilities that belong on any Mac

Onyx

A multifunction utility for Mac OS X which allows you to verify the Startup Disk and the structure of its System files, to run misc tasks of system maintenance, to configure some hidden parameters of the Finder, Dock, QuickTime, Safari, Mail, iTunes, Login window, Spotlight and many of Apple's applications, to delete caches, to remove a certain number of files and folders that may become cumbersome and more.
http://www.titanium.free.fr/

Macaroni

A tool which handles regular maintenance for Mac OS X, including the Mac OS X repair privileges process as well as Unix-style maintenance. You could do this yourself, but don't you have more interesting things to do with your time? Install and forget about it. http://www.atomicbird.com/macaroni

TinkerTool

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. http://www.bresink.com/osx/TinkerTool.html

SMARTreporter

A small utility that sits in the menu bar, checking the SMART status of your hard drive each time you start up and periodically afterwards. http://www.corecode.at/smartreporter/

Dropbox

Absolutely necessary if you have more than one computer or if you want access to some of your files from any computer (or smartphone) in the world. Also a great back-up solution that saves previous versions of files. First few GB free. (For PCs, too.) https://www.dropbox.com

Twitter Clients

These are my two favorite Twitter clients for the Mac. There are many out there.

Twitterific: http://iconfactory.com/software/twitterrific
YoruFukurou: http://sites.google.com/site/yorufukurou/home-en

Applejack

This application is invisible from the GUI, but when your Mac gets really sick, it's indispensible. After starting up in Single-User Mode ((hold down COMMAND + S on startup), typing " applejack " and then " a " for Autopilot will fix any number of hard drive problems and run routine maintenance scripts. http://sourceforge.net/projects/applejack/

Just for MacBooks and MacBook Pros

The last is a little tip, a little advanced, but if you follow these instructions exactly, you'll have no problem. Performing this modification will change the "wake" behavior of your MacBook. Now, it wakes up whenever you open the lid. This is great UNLESS the MacBook opens when you're carrying it around. Changing one setting will require to hit a key (any key) to wake the MacBook after the lid is opened.

1. In the Utilities folder inside the Applications folder, find and open the "Terminal" application. (Don't be afraid!)

2. Type this exactly (or copy/paste it) at the end of the bottom line (it should be something like: yourusername% ):

sudo pmset -a lidwake 0

3. The Mac will ask you to enter your password. Type it and hit Enter or Return.

4. Type " exit " (without the quotation marks)

5. Quit the Terminal application. Done!

 

Helpful articles for Beginners and Switchers:

Getting Started on the Mac
http://www.apple.com/support/mac101/ (English)
http://www.apple.com/jp/support/mac101/ (日本語)

Switching to the Mac
http://www.apple.com/support/switch101/ (English)
http://www.apple.com/jp/support/switch101/ (日本語)

The Mac Interface
http://www.macworld.com/article/143515/2009/11/switchersosxinterface.html

Hardware and Software
http://www.macworld.com/article/143514/2009/11/switchershardwaresoftware.html

Switcher Guide
http://www.macworld.com/article/143512/2009/11/switchers_guide_files.html