NumWorks - The graphing calculator that makes learning math easier.
MathPapa - Solves Algebra problems for you step-by-step
Learney - Knowledge aggregator for developers
Shiny Things - Perfect for students to improve their math abilities
eMathHelp.net - Site is created to help people learn math. Includes algebra, calculus, differential equation calculators and notes with many examples.
Qalculate! - Qalculate! is a multiplatform multi-purpose desktop calculator.