Uninstalling applications in Mac OS X is very different than uninstalling in a Microsoft Windows environment because Mac OS X has nothing like the Windows Registry. While most Windows programs include an uninstaller that can be run through using the Add/Remove Programs control panel, no such feature exists in Mac OS X and so most users simply move application bundles (see below) to the Trash. However, often times there is more to uninstalling than a simple drag-and-drop to the trash. This article will guide you on how to fully uninstall applications.

。。。我就是那个直接把不用的仍进废纸篓的人，ganz klar！因为找不到卸载途径

Most Mac OS X applications (anything that ends in .app), like Safari and iTunes, are bundles. The application icon you see in Finder (typically the Applications Folder) is usually a special folder itself, made to appear as a single double-clickable file. These "folders" contain all, or at least most, of the files needed to run the application, ie they are self-contained. This means that to uninstall these applications, you only have to drag them to the Trash. If you control-click (or right-click) on an Application icon, and you see "Show Package Contents", then it is a bundle.

Applications will leave behind preference files, and sometimes application support files, neither of which are stored in application bundles. Preference files can be safely deleted, but they usually take up negligible disk space — and, if you decide to reinstall the application again later, keeping the preference file means your settings will still be there. They are stored in the Preferences folder within your user's Library folder (~/Library/Preferences), or may also be stored in the system-wide Library located at the root of the system volume (/Library/Preferences/).
Application support files can take up anywhere from a few kilobytes to several gigabytes of space, depending on the application installed. Examples of applications that have large support files are multimedia programs such as Garageband and DVD Studio Pro. They are located in the Application Support folder within your user's Library folder, or in "/Library/Application Support/".
To remove an application's icon from the dock make sure that the program is not running at the time, then simply drag the icon off of the dock and let go. There will be a puff of smoke animation and the icon will be gone. This will only remove the dock icon/shortcut, and will not touch the application itself or any of its support files.
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英语好厉害啊