We have added the ability to generate arbitrarily-sized images from images that have been uploaded to Reason. A link now appears in the image preview page that directs users to the new ImageSizer module. On the ImageSizer module, users can specify the target, width, height, and crop style desired, and will get back a URL they can paste into their editor.
This is a user-facing example of Reason's new sized_image functionality, which promises much more control over the sizing of images for image galleries, etc.