Art of Problem Solving is a wonderful online mathematics resource, which includes online math classes, a variety of resouces, books, videos, contests, and a thriving community. It caters to all ages, from elementary to advanced high school.
New York Math Circle www.nymathcircle.org
NYMC offers special Mathematics enrichment classes for students – middle school through High School – on weekends during the academic year as well as an intensive three week summer program. Additional Talks, Workshops, and special topic sessions are also offered during the year for teachers and students. For details including course descriptions and requirements and dates, please refer to the NYMC website.
There are many mathematics summer programs around the country. Many advanced students attend and enjoy them. Here are a couple of list of summer programs:
- American Mathematical Society List of Summer Programs
- Art of Problem Solving List of Summer Programs