Opera Easter Egg - Opera 6 buildNumber()

Executing the ECMAScript statement,
window.opera.buildNumber()
will return the string:
"Hm, were you only as smart as Bjørn Vermo..."

The easiest way to see this is to type in the address bar:
javascript:window.alert(window.opera.buildNumber());

... and hit enter.

Bjørn Vermo is apparently an Opera employee, working in datalab.

Courtesy of http://www.howtocreate.co.uk/operaStuff/operaObject.html .