Boxopus lets you download torrents to Dropbox anonymously + w/o a Torrent client 14 years ago
I've done something similar with an IFTTT recipe, where I can email the URL of a .torrent file and it will be automatically added to a folder in my Dropbox. Then I have my torrent client setup to watch that folder for .torrent files. This works nicely when I'm not at my computer and want to start downloading something.
Here's the recipe: http://ifttt.com/recipes/100