How did I capture all of the icons posted on the Outlook icon pages? (Along with many more not posted here yet.)
Using Microangleo, IconCool editor, and other extractor utilities, you can extract the images from icon libraries, usually identified by the extension *.dll but *.exe can hold icons as well.
Tip: You can easily browse icons without using a 3rd party utility by right clicking on any shortcut, choosing properties and choose Change icon. For example, Outlook shortcut gets it's icon from C:Program FilesMicrosoft OfficeOFFICE11OUTLOOK.EXE.
When you use the extractor utilities, you'll discover that along with *.ico files, the icon libraries contain bitmap strips and other images. Outlook (and most windows programs) have the ability to create icons on the fly by layering two or more bitmaps. The programs can also reference icons in a strip using an index number. An example of a icon strip is on the top of each Outlook item icon page, such as this one on Calendar Icons.
When the ico files are opened in Microangleo or IconCool editor, you'll see there are usually 2 or more icons packed in the *.ico file, a large and small version and for newer applications, Windows XP icons in a higher resolution or color scheme.
A zip of all images included with most of the Office 2003 RTM applications is available here. It weighs in at a whopping 8+ megs. I used all of the image extractor utilities to extract the images from the files. It names the images using the file name that the image is packed in, which helps you learn which files are used to store icons.