To reach this egg, you can do a couple things.
Open Photoshop. While holding down the Alt key, click on the eye on the toolbar. The other way to get to this screen is by holding down the Alt key and going to Help -> About Photoshop. There you go, now you see the Big Electric Cat, the official mascot of Adobe Photoshop. After a few seconds, the credits will start to scroll.
That's not all there is to it. Hold down the Alt key to make the credits scroll faster. While holding down the key, click on the big eye once. Then, while still holding down the Alt key hold down the Control key. Now let go of the Alt key. Below the picture of the cat, above the scrolling credits, you will see about 60 messages.
If you can't get enough of the Big Electric Cat, hold down the Alt key before the startup screen loads next time you load Photoshop4. There it is!
Hold down the Alt key and click on the arrow in the layers palette. From the menu, pick Palette Options (you'll have to hold down your mouse button when clicking the arrow to get to the menu). It's Merlin! Click Begone! to get rid of the screen.

Try the following in MS Excel97 under Windows95:
Hit F5, and type X97:L97, and then hit Enter.
Now hit Tab and holding down the Control and Shift keys, click on the red/yellow/blue Bar Chart icon (
) on your toolbar.
Yeppers, you're flying. You have just activated the flight simulator hidden in a spreadsheet program. Isn't it cool? Want a challenge? Try to find the gray panel on the ground that has the credits rolling.

Try the following in Microsoft Internet Explorer 4.x under Windows95:
Select Help from the menu bar and click on About Internet Explorer.
Hold down the Control key and drag the "e" logo onto the Earth icon.
Release the Control key, then hold it down again. Move the e over the Microsoft Internet Explorer 4.0 text. The text slides off to the right, revealing an unlock button. Still holding down the control key, move the e Logo back over the world, and release it.
Press the unlock button. You'll get about 10 minutes worth of credits. It's a little boring at that point, especially without any music, but unlocking this egg was really fun, wasn't it?

Try the following in Microsoft Outlook97 or 98 (not Outlook Express) under Windows95:
Create a contact named Ren Hoek and select it.
Click on Help in the menu and select About Microsoft Outlook. Hold down Control, Alt, Shift, and click on the OK button.

Try the following in Microsoft Powerpoint 95 or 97 under Windows95:
Go to the Help menu and click on About PowerPoint. Click on the icon or image on the left.

Try the following in Microsoft Word97:
Open a new document and type zzzz.
Run Spell Checker (press F7 or right-click on the zzzz) and you'll be surprised by the word replacement it suggests.
Fun with the Thesaurus:
Open Word97 and type I'd love to see you naked. Highlight the word and press Shift + F7.
More fun with the Thesaurus:
Open Word97 and type unable to follow directions. Highlight the word and press Shift + F7. Who knew?!??

Try the following in any platform using Netscape Navigator 1.x or 4.x:
Press the Control, Alt and F keys on your keyboard all at once. FishCam!

Try the following in Riven:
From the start, make a right and go up the stairs.
Avoid the bridge. Instead, go down the stairs on the other side. Look for a door on the left. Slide under it and look along the right walls.
It is rumored that there are faces of programmers' children on the walls.

Try the following in Starfleet Academy:
In the mission called Balance of Terror, set a course for the Haxius system and warp there. The pod of space snakes will greet you. Attack them and they attack back.
In the mission called Common Ground, type, in capital letters, GNAT ATTACK. A swarm of gnats will appear.

Try the following in Windows95:
Click on any open area on your desktop using the right mouse button. From the menu, select New, then Folder. In the folder's name field, type the following exactly:
and now, the moment you've all been waiting for
Press Enter. Use your right mouse button to click on the folder again and select Rename. Type in the following name exactly as you see it:
we proudly present for your viewing pleasure
Press Enter again. Use the right mouse button to click on the folder and select Rename again. Type in the following folder name exactly:
The Microsoft Windows 95 Product Team!
Press Enter again. Double-click on the folder. If you did this right, a window with some animation will start playing with the names of the people that were a part of the Win95 Product Team moving around.
Screensaver (works in Windows98 too):
Right-click on an empty area in your desktop and choose Properties from the pull-down menu. Click on the Screensavers tab when the Display Properties screen pops up.
Choose the 3D Text screensaver. Then click on the Settings button. Type in volcano for the text. Click the Preview button after you hit OK to see the screensaver. You'll see the names of famous volcanoes.

Roll the credits:
Double-click on the clock in your system tray (or right-click on it and select Adjust Date/Time). Then click on the Time Zone tab.
Next hold down the Ctrl + Alt + Shift keys. Whole holding those keys down, on the map click and drag from Memphis, Egypt (point A) to Memphis, Tennessee (point B). Then click and drag from Memphis, Tennessee to Redmond, Washington (point C). You'll then see the credits of the developers and some pictures from Microsoft's building.
Screensaver (works in Windows95 too):
Right-click on an empty area in your desktop and choose Properties from the pull-down menu. Click on the Screensavers tab when the Display Properties screen pops up.
Choose the 3D Text screensaver. Then click on the Settings button. Type in volcano for the text. Click the Preview button after you hit OK to see the screensaver. You'll see the names of famous volcanoes.