It's called Boxopus. It's simple. Sign up for a Boxopus account. Then, pair your Dropbox credentials with tie site, and add as many torrents as you like (and as will fit into your Dropbox storage, once the downloads are complete, of course).
The Boxopus servers will then take care of everything. They will download the torrents and put the resulting files into a folder.
We'll have to see how long this service remains in place. If, in fact, you were using Boxopus to download copyrighted material, wouldn't you be violating one of the key Dropbox terms of service? That one is,
"You must not, and must not attempt to, use the services to violate the law in any way, or to violate the privacy of others, or to defame others."
We'd assume that downloading copyrighted material illegally would "violate the law." It's also unclear if Boxopus is using the Dropbox APIs properly, as well. At any rate, we wouldn't be surprised to see this service go the way of Torrific.
Boxopus founder Alex told TorrentFreak, “Cloud storage is an emerging trend, it’s obvious that sooner or later everything will be in the cloud. That’s why we decided to unite Dropbox and BitTorrent to make downloads as easy as 1 click, without using even a BitTorrent client."
Some sites, such as TorrentReactor, Fulldls.com, Vertor.com and Torrentzap.com have already added one-click support for Boxopus, meaning users don't have to add a torrent manually. Boxopus hopes that more sites will add this functionality in the future.
For now, the service is completely free and unlimited. That is only going to be good for the beta testing stage, though. Later, some limits will be imposed on free vs. paid accounts.