again, i like what you are trying to do with the colors. the first one works in this respect, as it seems you are trying to limit your palette. it has a nice effect.
merp on the second
sowwy.
the third is great. i have a pretty nice photoshop action for converting digital colors to black and white (complete with film grain). let me know if you would like to have it. it has options for different types of b&w films.
ps: i like the grain in the last shot.