I didnt really know where to put this, so i guess here is as good a place as any.
I stumbled upon this article while reading though some news stories. It shows the dangers and inconveniences which can be caused by over reliance on huge databases. I don't necessarily agree with the bloggers comments on police harassment, as it was the database errors which caused them to take the actions they took and stopped them from going out and arresting the real criminals.
http://www.robfisher.net/blog/archive/2006/12/29/police-harassment