Single-use credit card numbers (and one-time passwords) would help a ton. Multifactor authentication of any kind would also be good. The problem with all of the

Single-use credit card numbers (and one-time passwords) would help a ton. Multifactor authentication of any kind would also be good. The problem with all of these ideas is that they're harder to use than fixed CC numbers and passwords. I do like the convenience of being able to memorize a password or CC number though.