Nik Silver Efex
It looks like it has gathered in one place a lot of really great tools for B&W conversions.
I’m a little bummed that this is a Photoshop plug in, however. First, I’ve pretty much moved away from Photoshop for everything except printing (and I’ll ditch that too as soon as I can find something that gives me good enough control over that). The way of the future is not in Photoshop–it’s really showing it’s age now.