TVShows is an automatic torrent downloader for the Mac. It was designed to download TV show torrents when they are released so that you can automatically have your TV shows downloaded and ready after they air on TV. There is a great list of TV shows from which you can subscribe to shows that you regularly watch. TVShows is not a torrent client, it merely allows you to download .torrent files that you can later open with any torrent client. By default, TVShows is set to open downloaded torrents with your default client, but you can change this and the directory to which torrents are downloaded.
When you subscribe to a TV show, you can choose what episode to download first. There is a list of previously broadcast episodes with their dates, or you can simply choose to download the next episode to air. From the preferences menu, you can choose whether you want to download standard-definition episodes (350 megabytes) or HD ones (700). But those options are general, so all the TV shows you are subscribed to will download the same type. I use ted and it allows you to choose versions for individual TV shows. Another feature that ted has and I am not seeing here is the ability to check for new episodes manually. TVShows will check at regular intervals, but won't let you do it manually. By default, the minimum value is 15 minutes.