There are quite a lot legal torrents to download around the web.
I like Miro. It's a really nice media player, but it is also a well working torrent client. It has a vast database of legal torrents you just surf like in a browser and choose what you want to download. The nice thing is, you know if you see a torrent in Miro, you also know it's legal. Miro | Video Player | Free video and audio podcast player and torrent client.
Another example of legal torrents: I subscribe an IPTV service from my native Finland to here in Germany. I can watch this service normally over an IPTV set-top box connected to my TV, or from any computer. The service stores all shows on every channel I subscribe for four weeks, so I can watch them whenever I want to. I can also download my playlist as torrent by going to my playlist page and adding the complete playlist to Miro. This converts all shows I've chosen to torrents, which Miro then downloads automatically.
So, torrents are not automatically always illegal.