You missed a couple!
When you're in the menu with the big speed circle, press and hold the hidden button in the center of the circle for about 10 seconds. The Developer menu opens up, with lots of interesting stuff in there.
When you're at the main screen with the "Where To?" icon, press and hold the signal bars in the upper right corner for about 10 seconds to open up the satellite info. You can see the signal strength of all of the birds you're receiving, where the sun and moon are, and your estimated accuracy - and when the Dead Reckoning mode is active.
I think there may also be another hidden button on the "Where To?" screen that is in the upper-right corner opposite of the signal strength bars, but it's been a while since I've played with a 2011-12 model and looked for it. Press and hold around there for 10 seconds to see if something pops up. The hidden button is small, so you may need to poke around.
Don't forget the screen-shot buttons - hold the driver's side climate up, driver's side climate down, and the rear defrost buttons at the same time for 10 seconds and a screenshot will be saved to a USB stick plugged into the center console USB jack.
Dealer Mode is entered by holding driver's climate up, driver's climate down, and front defrost button for 10 seconds.
If you're lucky, you may be able to enter Engineering Mode by holding the driver's climate up and driver's climate down for 10 seconds, but that feature was only on some particular software builds of the radios. Most do not have that feature enabled. If you have it, you can disable the speed sensor lockout and be able to watch DVD's while moving without a Lockpick.
You can put the vehicle in or out of "Shipping Mode" by holding the front defrost and Enter/Browse button for 10 seconds. Supposedly, it turns off some features when the car is off to reduce the battery drain when it is sitting, but it also does something to the Keyless Entry feature - I can't remember what it does; maybe disables it so you need the key to unlock the car. Nice safety feature if you're paranoid of someone with a programmable key fob stealing your car.
One of my favorites - Hold the Down button on your steering wheel and cycle start button to "RUN" without touching the brake pedal for a nice dashboard light show!