I've played quite a bit with the B&W on my camera (FujiFilm 6900z) and, at the end of the day, the results it yeilds are nothing compared to taking in colour and then doing the rest in Photoshop.
I used Photoshop 7 at the moment (I use it nearly every day with work) and the easiest way to get a good B&W is to do the following (and this will work with all versions down to 4.0, probably more) -
image / adjustments / desaturate
then
image / adjustments / brightness and contrast
Play with the sliders to get the effect you want. I usually drop the brightness by about 10% and then up the contrast by around 20%. This pic -
http://www.pbase.com/image/18430663 - is about the best example I've made using this technique. I can upload the original picture if desired (or just drop me an email).
As has already been stated in this thread though, when you take the shot plan to have it in B&W. Just seems to help. Then again, compared to most of the people on this site I'm nothing but a weak amatuer
-Alex