10 Things about Hard Drives:
Also check out the guy's YouTube page, because it contains two other interesting videos from the domain of data recovery (and he seems to be somebody who actually knows what he is talking about when it comes to hard drives, not like some other people).
System 2008: What is Google Website Optimizer? – if you have a website (or work on websites) this is something to watch.
Credits: I’ve got the links for some of the videos from the Security4All blog.