I have a TrueCrypt volume that's been hanging around for more than a year now. It's fairly small (<5GB) and has a non-informative name. I don't remember where it's from; I know it's from my previous (or even older) laptop and has just been carried forward in the "things to keep" folder.
However, I have absolutely no idea what the password for the volume is. So, every now and again I give it a few guesses. Today was one of those days. Thwarted again.