"Steven Strogatz, an award-winning professor, takes readers from the basics to the baffling in a 15-part series on mathematics. Beginning with a column on why numbers are helpful, he goes on to investigate topics including negative numbers, calculus and group theory, finishing with the mysteries of infinity." Lovely series of online articles at the NYT explaining maths. Lots of good stuff.

"Being NOTES and SLIDES on a talk given at PLAYFUL 09, concerning CHARLES BABBAGE, HEATH ROBINSON, MENACE and MAGE" Awesome; shame I couldn't be there. I wondered where that link about Michie had come from a few weeks ago...

The Klein Four are "the premiere a capella group of the world of higher mathematics". Judging from this video: yes, so they are.