It's amazing to think how much welfare a single person's free work can add to the world. Basically FOSS but for learning math. I used this site ~12 years ago when taking calculus courses, and more recently I put it as a recommended resource on my syllabi when teaching those same courses. Apparently many others benefitted as well. A gift for exposition + selflessness + a permanent domain name (I'm guessing, due to his job at a university) = profit for everyone.
I had the honor of being a student of his. I was a high school student while attending college there thanks to a Texas program for gifted kids. As a professor he’s quite the character with his beard and his rat tail and his funny mannerisms. If you think his online notes are good, well, his lectures were an order of magnitude better those of than any other calculus class I’ve been part of. I wish he would make them available online.
