The Putnam Competition is the premier mathematical competition for undergraduate students in the USA. This collection contains tex and pdf files of Putnam problems and solutions with commentary, as well as links to secondary resources related to Putnam....
Here's a link to one of my favorite math news websites. It's always interesting (to me, at least) to see how sometimes even niche or obscure parts of math end up being applied to solve problems in ways I likely never would have dreamed up myself....
This is the main expository publication of the American Mathematical Society; it features articles on various topics at the forefront of mathematical research written for the non-expert, as well as community news, jobs openings, reader correspondence and more....
The American Mathematical Monthly is an excellent resource for mathematics enthusiasts, with articles selected for high quality exposition and broad appeal....