About a year ago my hard drive crashed. I lost 30k hands of poker, 70 gigs of MP3s, 100 gigs of movies, and about 6 years worth of programming code that I had written, including web libraries, and pretty intense graphics libraries, and my own custom game engine; I had even made a full-blown game (and was planning on releasing it as shareware), but that's all gone now. Not to mention dozens of documents of varying importance.

What did I learn from this? Not a damn thing. I still don't back anything up.