This is cool, and I never noticed it before. Go to www.yahoo.com and click on the exclamation point. If you have sound on, you should hear the classic, "Yahoooooo!" voice. Pretty cool.
Again, just click on the top portion of the exclamation point, the part I boxed in below.
Forum discussion at DigitalPoint Forums.

Comments:
Ramenos
11/06/2006 08:55 pm
That's fun but this voice is old. I tested it 4 months ago. ;)
Amit
02/06/2007 02:04 am
It's not just the top portion of the exclamation point, it's the entire exclamation point.
eboyblue3
08/12/2010 05:34 pm
That yodel has been changed to kid-type voice and at a faster pace!