You can't sacrifice partition tolerance – A convincingly (and amusingly) argued case that you can never trade off the P in the CAP theorem.
Topic discovery with Apache Pig and Mallet – This sort of thing used to be magic, now you can assemble it from off-the-shelf components.
The insanely confusing path to legal immigration – I've almost made it through my immigration story, knock on wood I'll be taking my citizenship oath in May after twelve years, but it's been tough to explain to my American friends quite how convoluted the process is. This chart will help!
Click dataset – Over 50 billion real-world HTTP requests. I'm certain there are identifiable elements in this data, but I think Arvind's right that researchers have proved this so convincingly that they won't bother to highlight them, and malicious users will never talk about it, so for some approximation of matters, it doesn't matter.