From WebOS Internals
This is a research page to store all found Easter Eggs (secrets which enable fun or interesting things).
Enable Developer Mode
In universal search, type the Konami code: "upupdowndownleftrightleftrightbastart" (without quotes). This easter egg will let you turn on Developer Mode. You should now reset your Pre. Credit to dsevil for the find.
Devmode can also be enabled by typing "webos20090606" (without quotes)
Additionally, you can unhide the DeveloperMode Enabler by altering the visible attribute for it.
Alarm Interval Toggle
On the Clock Preferences screen, enter "sixtyten" (no quotes) to toggle 1 minute or 5 minute intervals for alarms. You will hear an alarm sound confirming the egg took effect. (WebOS 1.4.0)
Hide Alarm Dashboard
To hide alarm dashboard notifications, on the preferences screen, double click the orange key (to force all numbers) and enter ""4231" (no quotes). (WebOS 1.4.0)
Landscape Mode Email
Typing "RocknRollHax" in the accounts list window will cause the email app to go into 'free' orientation mode. (WebOS 1.4.0)
If you open an email with the subject "supercowpowers" you will see three cows cascade down the screen over and over. Credit to "cwgtex" for the find (WebOS 2.0).
Works in WebOS 2.2.4 as well.
In WebOS 3.0.2 on the TouchPad, opening the same email reveals a graphic for a split-second reading, "iphone ota 2 team valve"