Buy.com authorizes credit cards for all items in an order whether the items are ready to go or are pre-ordered. While this may seem trivial to those who use regular cards, for anyone who uses a 'check-card', having them try to hold your money for weeks or months is highly inconvenient especially when they don't tell you this ahead of time. And their web site DOES NOT mention this.
Their response is that authorizing and billing are different processes.
I think the equivalent of taking your money and mailing it back to you is rather unethical. Authorizing the money now is no indication that it will be there when it comes time to ship. It's bad enough when the car rental companies do this, but I can understand them.