ParaGraph: a parametric graphing calculator. ParaGraph can graph multiple functions at once, perform numerical calculus, find extrema, do log plots, plot polar graphs, fit curves to data, do basic vector operations, and much more.
Extcalc is a multifunctional scientific graphic calculator for linux with features like graph drawing, graph analysis and calculating scientific functions including differentiation, integration and logic functions.
A graphing utility for the Pocket PC. User definable functions with 2D and 3D graph support. This calculator also supports matricies, lists, complex numbers and many math functions. Lua scripting is partially integrated.