These are all created using Photoshop. Enjoy!!
*Image>Adjustments>Channel Mixer and check the monochrome box.
*Play with the top three sliders.
*Make them add up to 100%.
*Here's some film emulation suggested settings:
Agfapan 25: 25,39,36
Agfapan 100: 21,40,39
Agfapan 400: 20,41,39
Ilford Delta 400: 22,42,36
Ilford Delta 400 Pro: 31,36,33
& 3200
Ilford HP5: 23,37,40
Ilford Pan F: 33,36,31
Ilford SFX: 36,31,33
Ilford XP2 Super: 21,42,37
Kodak Tmax 400: 27,36,37
Kodak Tri-X: 25,35,40
High Contrast: 40,34,60