Really, Really, Really, Really bad GUI:

My wife and I were trying to make an order at a well-used website. We were using current Mozilla Firefox3. She had selected a number of items to buy. All that was left to do was this: Select the month and year that our card would expire.

I clicked on the month. Nothing happened. I tried again. Nothing. There was a tiny arrow to the right of the month, the indicator of a drop-down list. I clicked that. Nothing.

At this point, it would have been reasonable give up, even after selecting so many things to buy. I was desperate. I Right-clicked on the month. I Right-clicked on that tiny little drop-down arrow.

Wait!

Something happened when I Right-clicked on the drop-down arrow. A few pixels shifted to suggest that I had selected it. Great, I thought. I pressed the down arrow on the keyboard, and the month changed to Feb. I down-arrowed to the correct month. I right-clicked on the tiny arrow for the year drop-down, and down-arrowed to the correct year. And then I placed our order.

If I hadn't figured out how to set the credit card's expiry, would I be entitled to kill someone? Almost entitled, perhaps?

Bad, Bad, GUI.