You can use curvemeister to do b&w conversions. It uses soft proofing, so this is only good in Photoshop with Curvemeister 2 or later.
1) dupe the image, set Photoshop's soft proof to Custom, and select "2.2 gamma"
2) start Curvemeister, and make sure the "support soft proof" option is on (see attached image). This will give you a monochrome preview image inside of Curvemeister.
3) pick a color space (I used Lab or HSB to begin with) and use curves, with or without masks, to get the image you want.
4) click apply
5) ignore the ugly colors, and convert the final image to 2.2 gamma
AFAIK, this is a new technique, and can be used for other Photoshop operations where you would normally use a de-saturate layer.
