I have a 2GB SanDisk Cruzer USB stick that I wanted to give to Kaellagh to use. The problem was that it had this tiny, annoying little U3 partition on it. Not only does it have an install file on it, but the partition is set up to look like a CD drive when you stick it in a computer (even on a Mac). I haven't had auto-run turned on for CD drives since the "feature" was added to Windows last century, so it didn't affect me, but it's still pretty sneaky.
Anyway, I wasn't willing to give the USB stick to Kaellagh with this rogue partition on it, ready to infect any computer she used it on. However, you can't just go to the Disk Management tool (or Disk Utility on the Mac) and get rid of the thing. It is untouchable in the Disk Management tool and invisible in the Disk Utility tool. Searches on Google for "remove U3 partition" came up with old sites that had links to a removal tool from SanDisk, but the links were all old web addresses that have since been bought by domain squatters since SanDisk didn't bother to keep them alive. I narrowed my search to only recent results and finally found what I needed.
From SanDisk itself, here is the page for the U3 Launchpad Removal Tool and here is a link to the .zip file itself. And just in case SanDisk decides to be awesome and re-arrange their web site yet again, here is a mirror on my own Amazon S3 space.
The tool is made for Windows, so be forewarned. It works fast and is easy to use, but it shouldn't be needed in the first place!