First Firefox add to Transmission extension that I have gotten to work, easy to setup! However, it doesn't recognize torrents from some sites where the url is something like: http://xxx.com/download.php/sometorrent.torrent?id=0000&passkey=a0aa0a0a0aa0aa0a0a0a0a0a0aa00000
Great! Glad you like it. Sure, I will fix it in the next update. I'll also add an option to enable it for any link. Which could be useful if you usually come across links that doesn't even have '.torrent' in them (but actually links to a torrent).
To get it to work, make sure the url you enter in the plugin preferences is like this: "http://SERVER ADDRESS:8181/transmission/rpc/' (for SERVER ADDRESS you should off course enter the ipadres or url of the server)
Transmission has a page @ https://trac.transmissionbt.com/wiki/MagnetLinks && also, there's another easy solution (without using this add-on): http://askubuntu.com/questions/122930/how-to-make-firefox-open-magnet-links-in-transmission
Works well, but I did have the same as others I got an unknown error, but it was just missing the port. It should look something like this if 9091 is your port: http://hostname.com:9091/transmission/rpc
Make sure you can reach the URL you've entered, by manually accessing it via Firefox. The URL should be something like http://127.0.0.1:9091/transmission/rpc and when you go there, you should be asked to log in.
Really nice addon. Thx to the author. Just two little missing things : handle the https connexions to the client and catch the file directly by clicking on the link (like SabNZBdfox for newsgroup). Thx again :-)