Melvyn Bragg's <a href="http://www.bbc.co.uk/radio4/history/inourtime/inourtime_science.shtml">In Our Time</a> frequently has mathematical editions.

Subjects have included: infinity, Indian mathematics, music and mathematics, Godel's incompleteness theorems, Leibniz vs. Newton, Fibonacci numbers, the Poincare hypothesis, negative numbers, prime numbers, Renaissance mathematics, pi, zero, chaos theory, symmetry and Archimedes.