OpenHantek is a free software for Hantek (Voltcraft/Darkwire/Protek/Acetech) USB DSOs based on HantekDSO. The UI is written in C++/Qt 4 and uses OpenGL to draw the graphs. It was tested with the DSO-2090, test results with other models are welcome.
OpenHantek has started as an alternative to the official Hantek DSO software for Linux users. At the moment it's basically running under Mac OS X too, but since this lacks udev you'll have to load the firmware by hand up too now.