A GTK+/Gnome2 graphical front end for the IW3HEV Vector Network Analyzer, also has a signal generator, and It displays graphicaly SWR, Phase, Return Loss, X impedance, Serial resistance, |Z| Impedanze, and Inductance, and capacitance.
Pixel Toaster is a portable open source framebuffer library for C++. It provides a fast and easy way to get your pixels on the screen. Floating point and truecolor pixel formats are supported on Windows, Mac and Unix.