The Two Best Colors In The World - Black and White

They always say there is more than one way to do something in Photoshop. Well, here is a real treasure of an article on B&W conversions right here by P.J. Morley. Mr. Morley shows, count them, four ways to convert your color image to black and white with a thorough explanation for each procedure. Of particular note is the Channel mixer technique. He gives several settings for emulating the tonalities of several B&W films.
For quick reference, here are the settings.
Fuji NeopanR +45, G +30, B +25
Ilford DeltaR +25, G +40, B +35
Ilford HP5R +47, G +47, B +6
Kodak Tri XR +35,G +28, B +37
Kodak T MaxR +30, G +32, B +38

But wait, there's more, and they are even more interesting.

These are the settings for creating an "Infra-Red" effect. Again, here are P.J.'s Channel Mixer settings:
Try these as a starting point. Note these don’t all add up to 100
IR Effect 1R +50, G +65, B -30
IR Effect 2R +80, G +100, B -100
IR Effect 3R +60, G +80, B -80
IR Effect 4R +70, G +40, B -50.

If you prefer a darker sky give a little tweak in curves to boost the contrast.

It's a great B&W article, check it out here.