It's true that some don't agree with my steps, which is perfectly AOK.
But the steps have kept my money secure and safe. I've had many friends and acquiesces that have lost money by not taking proactive approach to protecting their accounts.
For instance, a non-profit organization screwed up on my renewal and attempted to transaction twice. The initial transaction went through. Because of the way I do things, the second transaction didn't go through, that was attempted a few hours later. I then immediately canceled the card, and had a new one, with a new number issued. A few days later, a third attempted transaction happened, from the non-profit organization. Of course the third time also failed, because the card was canceled, but my bank notified me, because they keep record of all card numbers, and of course, attempted transactions.
Remember in the past six months or so, the situation with Target and others? It's better to be safe and sorry.
Should (pcpunk) contact all that has his card? If it's canceled, it really isn't necessary, because they can't get to the money. If a transaction is attempted, it shouldn't go through. However, if the bank allows it, and the card is canceled, the bank is legally on the hook to give you your money back, and if appropriate, any "overdraft" fees. If the last transaction was months ago with EBay as (pcpunk) says, then that would be a red flag, if it shows up overseas. It could be any company that has your card number that got hacked, for example.
Now, if the people that have your (pcpunk) card automatically pulls out their money out, I'd suggest you (pcpunk) change things around. For me, on my bills, I push the payment to the payee, from the bank. All the payees I send things to accept electronic payments, and usually takes 1 business day to get to them.
Best of luck.