At the high school I went to we had a 3D animation class running xsi softimage. It was a fun class and I eventually became the TA. I then discovered that all of the computers in the entire school district had been wired using fiber underground. This wasn't 5000 computers, but still it was a good 800 or so unused. For our 3D class most computers would be set to render and they would stay on all night. The next morning (usually over the weekend) we would come back to see if our work was done.
I had the genius idea to install the headless xsi renderfarm backend software (can't remember the name of it) on all of the computer in the district. This way the rendering could be greatly accelerated over the school district. The problem is the education license of softimage is everything the full retail version has with a limitation on multi computer rendering. After I ran tests on the software for a week planning to streamline the software into every computer, the school got a call. The xsi people called letting us know of our license restrictions. Because of this, the plan never went through. However, I never would of in a million years have foreseen a consequence like being charged 1mil because of the pissy school district.
Sometimes in the IT world when you think outside the box and it does genuinely help it only comes back to bite you in the ass regardless. *sigh*