I can think of 5, depending on how far you want to split hairs...
- Windows key on your keyboard
- Start button (on tablet PC's)
- Swipe in from the right (on touch screens)
- Mouse to the upper-right or lower-right corner
- Start button in the task bar
However, anything related to the charm bars breaks good UI design, since there are no visible elements on the screen to cue the user that something is there.