Lineal is basically a web-based calculator for linear algebra. It aims to outdo graphing calculators in usability and accuracy. Certain examples include the ability to save/restore sessions, trivially join together and break apart matrices and vectors without manually editing and resizing a copy, and add rows and columns to matrices on-the-fly (augmented form need not be stored). Perfect ratios are used so the accuracy of most operations remains perfect if the input is not floating point. Some important things aren't implemented yet, most notably: eigenvalue/vector stuff, diagonalization, and the Graham-Schmidt process.
It can do some basic math as well.