Some time ago a new feature was added to the site: magnet links. With this link it may be possible to download the .torrent file from another user through Azureus' DHT network. The main purpose of this is to give people an alternative way of getting the torrent file should the website hosting the torrents go down.
Please note that this feature is currently only known to work in (a recent version of) Azureus and in no other BitTorrent client. Also the torrent file needs to be "known" in the Azureus DHT network for the transfer of the torrent file to succeed: with less popular torrents this may be a problem. Last, as not many people know about the magnet link feature, it's likely a torrent will go seedless very fast if torrent site and tracker are down, making it still impossible to complete a download.
How to use Magnet links
Magnet links can be found on the Details page for each torrent, which can be viewed by clicking on this symbol: . You can identify the magnet link by the symbol. If simply clicking the link doesn't work, right-click on the magnet symbol and select "Copy Shortcut" (in IE) or "Copy Link Location" (in FireFox), then open it in Azureus by going to File > Open > Location in the menu.
Please use magnet links only when the torrent site is down and remember that they might not always work.
To Fansub Groups
There really isn't anything to fear from the magnet link feature. Magnet links have been "hidden" on the Details page for torrents to ensure visitors don't make a habit of using them even when your torrent site is online. Futhermore if Azureus downloads a torrent through the DHT network, it will still try to connect to the tracker first -- so if you like to gather the statistics from your tracker, this will be unaffected.
If you really don't want visitors to use the magnet link feature, you can set the Private flag in the torrent files you create. It appears Azureus is properly obeying this tag and does not allow torrents with this flag set to be downloaded through the DHT network, which essentially disables the magnet links.