<p>Does anybody have a suggestion for a java library that performs automatic cropping and deskewing of images (like those retrieved from a flatbed scanner)?</p>

ImageMagick
can do that; you can use the
ImageMagick Java bindings
.  The
auto-crop
operator is probably what you're looking for.  Automatic deskewing is a much harder problem and involves some significant image processing; I'm not sure if ImageMagick can handle that.  If you can figure out the skewing parameters using something else, ImageMagick can definitely unskew it for you.