Security & Human Factors
Shorter passwords on web sites look like a good idea. Although I'm not at all a security expert, I would think it's a lot more difficult to crack passwords though brute force on the web, as someone should see the repeated attempts before they bear fruit. Files produced by desktop applications such Winzip or Excel are easier to crack that way: just copy the file you want to get into, and let some piece of software try millions of combinations per second till it pries the file open.

See, I'm still linking to Nielsen when he makes sense. But credibility is not an unlimited commodity.