Currency. Exchanging currency for travel is horribly inefficient and costly. Legal pharmaceuticals. Hard to sort the legitimate sites from the scams and coun

Currency. Exchanging currency for travel is horribly inefficient and costly. Legal pharmaceuticals. Hard to sort the legitimate sites from the scams and counterfeits. Anything involving PayPal. (The reasons have been discussed on HN ad infinitum, no need to repeat in this thread.) Bitcoin. The dominant exchange is buggy, secretive and untrustworthy. The best alternative is to actually send cash in the mail to strangers.