Power PC Graphing Calculator 
Graphing Calculator Code Name: NuCalc
Turn on Balloon help and go to "About Graphing Calculator...".  Then 
click the "Credits" Button.  
•There you want to simply drag the mouse over the window containing the credits.  
•Go to the next page and drag the mouse over both sides of that window.  •Also, Balloon help the CSC button in the full keypad to see at the bottom "c.f.E. Rutherford, Phil.  Mag. 21, 669 (1911)".  I believe this is the nuclear physicist (also known as Baron Rutherford) who, in 1911, worked out the nuclear theory of the atom.  
•Finally, drag balloon help over the application's icon itself.

In the 3D Surfaces Demo mode of Graphing calculator the last demo displays the graph for the equation z=cosnø (The ø is supposed to be a theta, which is Option-T in the application).  You can speed up the demo by pushing Tab.  After this graph is displayed it will replace the checker board texture with the Apple logo for the same equation.  Once it displays the newly generated graph it will restart the demo, but by pushing Return, while the Apple is still there, you can stop the demo and generate a new 3D graph.  You should notice that the Apple stays, and will do so until you quit, run a demo, or switch to 2D.  
From: Chris Callac (ChrisC1234@aol.com) 

Native Mode
Hold down Option and Shift when getting info. on a 
native Power PC application.  You will then see a list of 
credits of those who provide native mode.

Power PC Control Panel
From: Peter F. Jarvis (st92kgmr@dunx1.ocs.drexel.edu) and John Kessler (Riten@aol.com)
With a PowerPC Upgrade card installed, go to the Power Macintosh Card control panel and hold down Command-Option while opening the control panel. A picture of the design team will appear. Turn on balloon help and click where the people's mouths should be.  It will say funny things in the balloons.  

For example, in the mouth of the guy wearing glasses and a blue shirt will say the following: "Top 5 resons Apple should move to Texas: 5) Don't have to be an Apple CEO to afford a house. 4) Most Texans don't live in Williamson County. 3) Texans don't place 'The' in front of highway names. 2) Blue Texas sky, hot Texas summers 1) Real Mexican food."

Also, just hold down Option and open the control panel. A check box appears that lets you choose to bypass a RAM test a startup.

RamDoubler Native Power PC Program Get Info Trick
From: Chaz Larson (chazl@leonardo.lmt.com)
...and: Matvey Palchuk (mapst57@vms.cis.pitt.edu)
I am aware that this is a RAMDoubler egg but I have had so many messages regarding this egg I decided to include it.  While using RamDoubler and selecting a native PPC application, hold down command-option and get info for the application.  You will see at the bottom of the info window: "Note: Sleep is a poor substitute for caffeine!"  This only persists for the initial display; if you cover the info window with another window and then uncover it, the text will revert to its normal note about different memory requirements with VM on or off.  Be sure to hold down Command-Option and then let go once the window is up.

It varies with versions on wether you can only hold down Option-Command-I to see the egg or you can just hold down Option and select "Get Info..." from the pulldown menu.

SimpleSound
This new Desk Accessory for System 7.5.2 (PCI Macs) has an easter egg in it too.  Click on the icon in the "About SimpleSound..." window to see the name change to "Kip Olson".