QSL is a free (LGPL), Qt-based C++ library that provides classes for data visualization and numerical computations. At this time only the visualization classes are being written but in the near future we plan to integrate routines inspired on those in GSL http://www.gnu.org/software/gsl in a cool C++/Qt fashion.
Although QSL is in it's first steps, here is a demonstration of what it can already do:
