B+W Variations, a component of The Variations Suite tackles the tricky problem of converting colour into monochrome. Eight different treatments are available simulating different colour filters, Tri-X film and with options for adjusting contrast and adding grain.
B+W Variations CS2 is now out. It works with Adobe Photoshop CS and CS2. There are no new features in the script, so if you are still using Photoshop CS you do not need to upgrade. I've also added a gallery with a complete set of conversions for the same image to give a better idea of what the differences in treatments do.
03 Mar '06: V1.2 is available. What's new?
It's often difficult to choose what looks best in B+W, so the script's ability to create and save multiple previews with different options can be very handy. You can add a description to each set of previews, so you won't lose track of what you've done.

All the scripts in The Variations Suite work in a similar way, please refer to the instructions for installation, use and batch operation for a full explanation.