This is one of my personal favorites. It's an amazing effect to have in your arsenal.

This guide features the best ways to make color images black and white and how to achieve greater contrast. Translatable.

This tutorial is sparse but really takes out the magentas in Office screencaps. Translatable.

Non-translatable tutorial that really brings out blues in images. PSD included.

5 step tutorial that is easily done and great for The Office. Contains step-by-step instruction and layers tablet.