[math-fun] The "math pages"

http://www.mathpages.com/ contains an interesting collection of essays about a lot of mathy subjects. According to a hard to find note, they were written by "Kevin S. Brown." I can't vouch for them all, and there also are some broken links unfortunately,... but some seem highly insightful, and the amount of work it took to write all these was very large. Also, you can buy book version -- he self-publishes books.