Geometry Online - A good source for challenging geometry problems. This page also gives the NCTM standards, the Texas state standards for geometry, and a glossary. This page is a great source for algebraic word problems. Teachers can find good problems to use in lessons involving problem solving, quadratic equations, and other topics. A reference page for mathematicians.
Teachers can also find papers written on different mathematical topics here.
A reference page for anyone in education. Online Education - This page directs you to other pages that deal with education, lesson plans, and related organizations.