I went to Apple's site to get the qualifying $9.95 iLife disc since I just bought my Macbook from Amazon. What I didn't realize was that I had an existing Macbook in my cart from previous! Oops, good thing they had the cancel order tab!
I was mutlitasking and wasn't really paying attention. I never really thought that old item stay in your cart like that. I'm usually pretty careful when making online purchases, but for $9.95 I didn't really think about it. It wasn't until the order confirmation screen where I noticed the $1500 price tag.