Except scientific (non public) projects I also have some general interest projects:
MathGL is a free library of fast C++ routines for the plotting of the data varied in one or more dimensions. MathGL has more than 40 general types of graphics for 1d, 2d and 3d data arrays. It can export graphics to bitmap and vector (EPS or SVG) files. It has OpenGL interface and can be used from console programs. It has functions for data handling and script MGL language for simplification of data plotting. Also it has several types of transparency and smoothed lightning, vector fonts and TeX-like symbol parsing, arbitrary curvilinear coordinate system and many over useful things. Finally it is platform independent and free (under GPL v.2.0 license).
PocketMK is small program for PocketPC which simulate famous Russian calculators MK-61 and slightly extend it.