my client uses on her site the wpDiscuz Media Uploader addon, but her users uploaded large image files. wpDiscuz settings allow to set the maximum image size to 1MB, but that's still too much. My client has over 20 000 comments on one of her pages, and it's growing fast.
We use the plugin Imsanity to limit the uploaded images dimensions (width/height), but the plugin doesn't fire on your plugin's upload. Id your plugin using the standard wp_handle_upload hook? Or is there some other way how to limit not only the file size of the images, but also the max width/height?