Yeah, I seem to recall giving a pretty complex answer to this before in terms of how you could take an off-white shapefile image and convert it to an image, but the simple answer was what jim said in his first post:
- Load the shapefile data up (I'm assuming you know how to do this?)
- Maximize opacity if needed/relevant/applicable
- Hit the print screen button
- Paste it into MSPaint or applicable program, and save it
As far as removing off-white backgrounds in the map region itself is concerned, you can take it into Photoshop/GIMP, isolate regions by color and delete them to get rid of pesky pixels and uneven color variations within the borders. If you want the borders to be one color, you can also (once finished - but keep a copy in case you mess up) take it back into MSPaint and convert the canvas to black and white, but keep in mind that anything that is not perfectly white will be converted to black, so clean the image up prior to that accordingly.
