My YouTube channel - See here dozens of lecture recordings of mine from various courses, including Integral Calculus, Vector Calculus, Statistics, and Precalculus.

3Blue1Brown on YouTube - Grant Sanderson's celebrated 3Blue1Brown videos use animation to illuminate mathematical concepts in a whole new way.

Numberphile on YouTube - A series of short videos on fun proofs, paradoxes, games, and open questions, presented by a rotating cast of mathematicians and with a bent towards number theory.

Veritasium on YouTube - Mind-bending and amazing math and science videos. I was blown away by their recent 30-minute documentary on Incompleteness.

Mathologer on YouTube - Surprisingly accessible explanations of hard and beautiful math.

Fermat's Library - A platform for illuminating academic papers, including a free online repository where you can annotate and share your papers.

Terence Tao's blog - My favorite mathematician and possibly the smartest person on the planet, the modern-day Feynman of mathematics.