1001 things to do with liquid nitrogen, and lots of other fun suggestions can be found in this MetaFilter thread that started with a link on how to make home-made ice cream in just 30 seconds.
The fifth Harry Potter book will be available in a couple of days. The Scotsman has run a three-part article about Joanne K. Rowling these past days: part one: The JK Rowling story, part two: In the eye of the storm and part three: The legacy of Harry.
Link via 2020 Hindsight.
Happy Birthday, Sheila!