Qt

"SpeedCrunch é uma calculadora rápida de alta precisão para ambiente de trabalho."

"Qtractor é um sequenciador de Audio/MIDI multifaixa escrito em C++ com recurso às bibliotecas gráficas do Qt4"

"Qtractor is an Audio/MIDI multi-track sequencer application written in C++ around the Qt4 toolkit.

"Qsynth is a fluidsynth GUI front-end application written in C++ around the Qt4 toolkit using Qt Designer.
Eventually it may evolve into a softsynth management application allowing the user to control and manage a variety of command line softsynth but for the moment it wraps the excellent FluidSynth.
FluidSynth is a command line software synthesiser based on the Soundfont specification."

"QSampler is a LinuxSampler
GUI front-end application written in C++ around the Qt3
toolkit using Qt Designer. At the moment it just wraps as a client reference
interface for the LinuxSampler Control Protocol (LSCP)."

"A simple Qt application to control the JACK server daemon. Written in
C++ around the Qt4 toolkit for X11, most exclusively using Qt Designer."

"LinkStatus é uma ferramenta "Open Source" para verificar os links da sua página web.