The Quadratic Equation Solver posted on this page solves for both real and imaginary (if applicable) results. Also on this site: solvers for the Cubic and Quartic equations, N Equations in N Unknowns, Eigenvalues and Eigenvectors, Cubic Spline Interpolation, Numerical Integration, and Least-Squares Data-Fitting. - 
AKiTi.ca

A website with a database of information on a variety of units of measure. Look for new perspectives on the magnitude of any physical quantity. Numerous scientific & engineering charts, graphs & nomographs. Explore & get calibrated for your next technical challenge! - (www.units-of-measure.com) - 
Perspective Block

Just a small blog talking about latest mathematics news and general sciences. Including basics to advanced math, physics, interesting facts and some math for fun. - 
The New Math