Turns out the primary market for them (the TOR black market site The Silk Road) has been shut down.

Bitcoin value has dropped from $138 to $80 in the last 8 hours.

Fascinating story of ineptitude (and likely NSA snooping fed to the FBI) in the founder's downfall.

Even funnier: the FBI seized the site and all it's BitCoin accounts (some $4,000,000 worth) of the drug dealer user accounts.

Many of them shipped out drugs they now can't get paid for and others paid for drugs they can't now get.

read it all on reddit:

http://www.reddit.com/r/SilkRoad/