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Manages all your passwords. many apps talk to the keychain for you to get things like Exchange Server credentials, but it also lets you just put in passwords records yourself so you can keep records of frequent flyer numbers or bank account numbers.
Dashboard (Tiger OS)
Download oodles of widgets from Apple site.
Quicksilver (
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Tiger OS)
http://mac.softpedia.com/get/Utilities/Quicksilver.shtml
Quicksilver allows you to navigate to what you need quickly and easily, while keeping your hands on the keyboard. For example, if you want to launch an application hidden in the depths of your file system, simply activate Quicksilver with a keystroke, type a few letters of the application's name, then hit Return or Enter to launch it. When you don't need Quicksilver, it keeps out of your way, preserving screen real estate. (Doug, Diane and Debbie are using)