If your computer work entails frequent use of special characters, the OS X built-in Keyboard Viewer can make your life easier. This small window shows a live view of the characters available on the keyboard given the currently selected language and any modifier keys pressed (shift, option, etc.). An optional pulldown menu provides viewing the mapping for webding and wingding fonts, as well.
To access the Keyboard Viewer, it must first be enabled in the Input Menu (which must also be enabled) through the system preferences. Open the System Preferences (Apple Menu -> System Preferences…) and select International from the top level. In this configuration window, select the Input Menu tab. The resulting window should resemble this:
In this window, check the boxes next to Keyboard Viewer (near the top of the scrolling area) and Show input menu in menu bar (at the bottom of the window). If it wasn’t there already, a flag will appear in your menu bar corresponding to the language you have currently selected.
Clicking this flag icon will open the Input Menu which will now include the Keyboard Viewer. Clicking this option will open a small window showing a graphical representation of your keyboard like the one below:
As you press keys on the keyboard, the corresponding key in the Keyboard Viewer darkens and any changes to the other keys will be reflected. In the image above, the option key was pressed and the characters that would be typed using the other keys while option is held down are shown. Pressing shift in addition to option reveals another set of special characters.
The Font mapping: pulldown menu at the bottom of the Keyboard Viewer can be changed to webdings or the wingdings variants to reveal the character to keyboard mappings for those fonts.
If you use Greek symbols in your work, you may find it convenient to check the box next to Greek keyboard palette in the Input Menu window of the International System Preferences window shown above. You’ll then have a Greek flag option in your Input Menu which will allow you to switch over to Γρεεκ characters. The Keyboard Viewer will reflect this change and allow you to type Greek characters directly into any application.