Organize WP media uploads by wp-content/{year}/{filename.ext}. This plugin has no settings, it just works. It's best to use this plugin at the start of building a new website since changing the upload directory after you've already uploaded any images via the WP Media Uploader will break things.
Be sure you want this as your upload directory structure, once you start using this plugin it's not easy to go back! That's not to say the plugin doesn't work, just make sure you really want to use it before you actually do. :)