Gear up landings are always an expensive proposition, but I believe this takes the cake (click the picture for the full story and more pictures):

It turns out that this is nothing short of pilot error. As a taxpayer, you would like to think that the pros in the USAF are infallable, but as a pilot with only about 100 hours, I take from this the lesson that no pilot is ever too good or too experienced to make mistakes. I believe that all pilots will, at one time or another, make a mistake. You just have to hope that the mistake that you'll inevitably make is neither deadly nor expensive.

--Chris