If you wish to listen to a YouTube essay heavy on examples of great intonation by female singers, check this out.  This combines a review with clips of the artists to illustrate the point.  You can also google "Most Difficult Songs for Female Singers" to find a variety of playlists covering different time periods.  Something for every age. 

I'm sure @drpaladin would enjoy this!  It fits his style by including entertainment and artistic criticism.

Intonation also describes how a voice rises and falls in speech.  

The world would be a very dull place if everyone spoke in monotone and didn't use intonation. 

Imagine the intonation of the hiker who meets a big surprise on the trail:

"Nice Kitty. NICE KITTY!"