First, the simple ones:

Shift : Enter uppercase letters.  Press and release, then press the key you want.  Press twice for CAPS lock.  Press a third time to clear the shift state

Sym :  Brings up a list of the symbol characters.  You can scroll through the list by dragging or flicking.  You can also press a letter on the keyboard to filter by that letter.  Pressing another letter with a matching symbol key will change the filter.  Press Sym again to clear dismiss the list.

Orange :  Selects the alternate keys on the keypad (the numbers and symbols printed on the keys).  Press twice to lock to this input mode.  Pressing a third time clears the mode.

Center : Switches to card view, allowing you to scroll through your applications

Now, the more complicated ones:

Cursor movement:  Press and hold the Orange key () then swipe on the display to move the cursor.  Left and right work in move input fields, up and down will work in some.

Text Selection:  Press and hold the Shift key () then swipe on the display to move the cursor.

Cut, Copy and Paste:  Press and hold the gesture area then press X (cut), C (copy) or V (paste).

Screen shot:  Press Orange + Shift + P.  Note: You must hold all three buttons at the same time.  Images will be saved in the screencaptures folder in the Photos app.

Reboot: Press Orange + Sym + R.  Note: You must hold all three buttons at the same time.

Bold: Press Sym + B.  Note: This only works in Rich Text fields, such as e-mail.  If a selection is active then bold is applied to the selection.

Italics: Press Sym + I.  Note: This only works in Rich Text fields, such as e-mail.  If a selection is active then the selection is italicized.  Also, if you don’t press another letter (such as Q) while still holding Sym after doing this combination it will insert an i with an accent into your text, replacing your selection.  Use with caution.

For more information check out Palm’s list, this Pre Central Keyboard Tricks post or the excellent Palm Pre Tips and Tricks post.