Torrents is a great way get traffic and create long lasting stream of traffic. You don't need to use warez or anything. You can use legitimate things like your own e-book or an trial version. For example Adobe no longer offer trial versions of any old CS software. Even I had to search through net to find the CS6 trial.
So you can create a nice landing page and upload it along with the software. Don't use passwords or anything and keep everything clean. Make sure to use something related to the main download item you upload.
You will get lots of direct traffic if you do all right. I don't know if this will be good for AdSense sites but if you are looking for subscribers or for CPA site traffic will be fine.