Use the keyboard viewer if you are looking for special or foreign chars or if you just forgot where to find the backslash e.g.
1.: Choose Apple menu -> System Preferences and click International
2.: Click Input Menu, then toggle the checkbox next to Keyboard Viewer
3.: Toggle the language whose keyboard layout you want to use
4.: Choose Show Keyboard Viewer from the Input menu (international symbol) on the right side of the menu bar (to the left of the Time)
So you get this... very useful:
Activating the Keyboard Viewer for Special Characters