While not a credit card, I use Green Dot (pre-paid Visa/MC) for all of my online purchases. I control how much money is available to the account. I only credit that account with whatever I need for the next week or two (or for one time large purchases). Online companies like to store your account data regardless of whether you want them to or not. If the account is ever hacked, only the (very) limited funds I keep there are at risk.
Credit cards are fine for emergencies, but I know I had problems with them back when I held them. It was too easy to make that compulsive purchase. With a pre-paid Visa, I can only spend as much as I have in the account (usually no more than $50).
-Wolf sends