Yes, Dave has a good way of doing that, and when You have done it to a photo you tend to get some unwanted spots. What you do then is add a gaussian blur (how much depends on the size of the spots/picture) and when all is blurred, the magic comes with this last step: Image>Adjustments>Brightness/contrast.
Drag the contrast bar way to the left, make sure you keep the white white by using both bars. You might need to do this step more than once. And if you feel that it went to far (to many jagged lines) just go back to the blur step, and apply less blur and redo the brightness/contrast.
If you are going for a print on these images a great thing to do ones you have the line-art is to "convert" them into vectors and use in Illustrator, that way the lines will come out sharp as knives
A fast way is, copy layer to a new channel, make marquee, invert marquee, generate path in paths, and you have the paths, just copy and paste in Illustrator and give it a fill color. Now you can print it any size you want without having to think about resolution.