class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
more info about the class
$handle->image_precrop = array(-34, 0, 98, 100);
So here is a Release Candidate 0.27RC1, which implements a mean to crop before resizing.
The cropping is set with image_precrop, which accepts the same type of parameters as image_crop.
For instance:
This will crop the image before eventually resizing it.
Note that both image_precropand image_crop can be used together. The first one crops before resizing, the second one after resizing.
The test suite looks OK, but I haven't tested it extensively. Feedback would be appreciated.