Some important numbers

Vi Hart, Mathematical Amusements

Building Houses

Paul's Math Notes

Lego Calculator

Inertia

A sensory homunculus; a motor homunculus; the two, together

Pictures of Brains

physics lectures

numbers

Steven Strogatz on Math, in the Times

Wolfram Demonstrations

Transfinite Mathematics

Lots of Logical Systems

Foundations of Mathematics

Brownian Motion