Other math competitions

If you enjoy participating in math competitons, check out the list of what is available in high school here:
http://www.albanyconsort.com/contests/contests.html
Of those listed here, TJHSST participates in the AIME, AMC 10 and AMC 12. school wide, at the school. They typically send a couple of teams of 20 to the ARML held at Penn State. The Dept. of Energy holds a math competition in DC, but not every year. TJ usually prepares studnets for the IMO after participating in the USAMO. TJ also competes in the Mandelbrot. Many students compete in the USAMTS as individuals. These are all events that can lead to a math letter as well.
If you do not attend TJ, your high school may participate in these competitions as well. Often it just depends on getting a math teacher to sponsor a club. So if you have an interest, speak up to give yourself the opportunity.
The above website has sample problems for each of the contests.