Selective coloration of a B&W image.

Many variations of a B&W photo with selective coloration get posted; the red umbrella in a B&W rain storm comes to mind.
I post process with Aperture and NIK. I was wondering if there is a plug in to do selective coloration or if one could use those programs for the effect.
I no longer have PS and wouldn't purchase it just for that task.

Some of our photo gurus may have better answers but here are a few tutorials using tool that are built in to Aperture. The first one seemed to me to be best

How to Add Color to a Black and White Image Using Aperture - YouTube

Aperture - Selective Black & White - YouTube

Thanks,
I guess I should have thought of YouTube!

Yea I was going to reply, but I don't use Aperture or Nik, I am a Lightroom user.

I did this on Silver Efex on NIK. I have some more playing around to do.