Did you know there was a 150+ page manual for the iPad? It's an Apple secret.
The manual is impressive, but it's a bit too complete. It describes some VoiceOver features that didn't make it into the shipping product (some rotor controls).
Here's the current list of iPad accessibility gestures, taken from the manual:
Navigate and Read
Tap: Speak item.
Flick right or left: Select the next or previous item.
Flick up or down: The effect varies depending on the Rotor Control setting. See “Using VoiceOver” on page 110.
Two-finger tap: Stop speaking the current item.
Two-finger flick up: Read all, from the top of the screen.
Two-finger flick down: Read all, from the current position.
Three-finger flick up or down: Scroll one page at a time.
Three-finger flick right or left: Go to the next or previous page (such as the Home screen or Safari).
Three-finger tap: Speak the scroll status (which page or rows are visible).
Four-finger flick up or down: Go to the first or last element on a page.
Four-finger flick right or left: Go to the next or previous section (for example, on a webpage).
Select and Activate
Double-tap: Activate selected item. Touch an item with one finger, tap the screen with another finger (“split-tapping”):
Activate item. Double-tap and hold (1 second) + standard gesture: Use a standard gesture.
The double-tap and hold gesture tells iPad to interpret the subsequent gesture as standard. For example, you can double-tap and hold, and then without lifting your finger, drag your finger to slide a switch.
You can use standard gestures when VoiceOver is turned on, by double-tapping and holding your finger on the screen. A series of tones indicates that normal gestures are in force. They remain in effect until you lift your finger, then VoiceOver gestures resume.
Two-finger double tap: Play or pause in iPod, YouTube, Voice Memos, or Photos. Start or pause recording in Voice Memos. Start or stop the stopwatch.
Three-finger double tap: Mute or unmute VoiceOver.
Three-finger triple tap: Turn the display on or off. (This is known as the "screen curtain" feature. For my mother it's a bug, not a feature. It's too easy to go from mute/unmute VoiceOver to blanking the screen.)There's also far more to the zoom feature than I'd realized. This User Guide deserves a bit of publicity.