I did some Googling and found a few images to prove (to myself) that I'm not crazy.
|Painting a Darker Color under the Chair Rail - Image via Sköna Hem - Sliten Symfoni|
|Painting a Darker Color under Chair Rail - via Apartment Therapy of Kim Johnson's bathroom|
I might be pulling out the paint soon. Our high ceilings make this look much easier to pull off. The color won't be nearly this dark (although I love it).
If you have a vote, chime in with a comment! Do you like the dramatic flair of a darker paint underneath the chair rail? Or is monochromatic more your look?