Here's a short list of some singers I've found.

The Gals
Stacey Kent
Veronica Martel
Cheryl Bentyne
Susie Arioli
Queen Latifa (the Dana Owens Album)
Keely Smith

The Guys
Michael Buble
James Darren
Ronnie Milsap
Steve Lawrence (& Edie Gorme)
Boz Scaggs
Earth, Wind, and Fire

Some International Artists
Amr Diab (just plain awesome Egyptian)
Asala (Syrian)
Ishtar (French)
Shreya Ghosal (India)

Check 'em out on iTunes.

Add to the Gals list, Robin McKelle. Oh wow! This gal rocks! Search for her on iTunes or Amazon for samples. You'll buy!