What is BitTorrent you ask? BitTorrent is simply a file distribution tool. Large files are broken down into smaller pieces, and then shared among many users. What does this mean? Well it means you can find practically anything you want online. This is the method that Pirates used to release Star Wars Revenge of the Sith out onto the net. In order to utilize BitTorrent, you need a BitTorrent client. Just note that allot of the stuff up there is copyrighted stuff and downloading it may infringe on copyright laws.
Here are some of the more popular ones:
To find your favorite TV shows, Music, Applications, etc, you can search for the Torrent you want at the following sites:
The Pirate Bay
Here is a good FAQ site on BitTorrent: