It happened to me last summer, and I'm still not sure how. I never used that checking account to purchase anything online. I always use my credit card online, and never for anything else. My line of thinking is that if someone gets my credit card number, so what? They can't do any lasting financial damage.
I was buying my girlfriend a $1.59 20oz drink and the register said insufficient funds. I freaked out. Got a call the next day from my landlord saying my rent check had bounced. I freaked out even more (I ALWAYS keep several months rent in my account).
A trip to the bank the next morning started the process of fixing the problem. Turns out someone got my account number and made a $3000 donation to the Arizona republican party two days before I discovered the problem.
I got my money back, and new accounts, but it took about two weeks (those Visa commercials that say they replace the money within 24 hours aren't accurate). I had to find a way to proove to the bank that I'm
not a republican and had no desire to make a donation. It really sucked because they cleaned me out and I only had about $14 in my wallet.
I'm still curious how in the hell they accepted a donation of that size without ID? And multiple calls and two letters to the Arizona GOP didn't even get me an apology. It
did however get me on a John McCain propaganda mailing list

, which was exactly what I wanted after going through that hassle

.
I never give my debit card to cashiers. The only thing I can think is that someone behind me in line in a store saw my card and managed to memorize the number or took a picture of it with their phone. I'd love to know who did it (and send them to gaol

).