Both these give you a simple way to search for things you want. They use IMDB and the like to give you a big list of results. You add what you want to your collection and in the background they scurry off to torrent sites or usenet and downloads it. Then they name everything nicely and stuff then in your Plex library.

You can set them up to use specific torrent sites. Download specific qualities, or more likely an order of qualities by preference and all sorts of other tweaks.