It's still worth noting that no hidden service has been deanonymized through a direct attack on the Tor network. Maybe that's because LE is always 3 years behind the curve... If you're talking about trades within bitcoin, there's Zerocoin. http://dkn255hz262ypmii.onion/index.php?topic=152682.45 If you're talking about exchanging bitcoins for government-controlled currency, cash is the only (potentially) anonymous, untraceable government-backed currency, so cash for bitcoins seems like the only thing that would work. Then you're back to face to face meetings. haha, I needed something to cheer me up man.