The Uploader plugin creates an Uploader role with the capability of uploader_upload for file uploading within wp-admin after credentials have been input in wp-login.php. This allows your WordPress users to be able to directly upload to your server. This plugin has a number options that can be set. You can set an option to be notified when the file is uploaded, where in your uploads directory the files will be uploaded to and what type of files are acceptable to upload.
This plugin integrated the efforts of the Uploadify project for its uploading capabilities. Uploader is a free and open source plugin available on the WordPress plugins directory.