Free for non commercial purposes:
VideoLab - Capture, process, analyze, adjust and playback video. Supports DirectShow, DMO and VFW.
SignalLab - Digital Signal Processing (DSP) library
AudioLab - Record process analyze visualize and playback audio. Supports DirectShow, DMO, ACM and WaveAPI.
VisionLab - Basic computer vision library. Currently implementing Motion Detection solutions. Comes with full set of capture components.
PlotLab - Fast data Plot library - Scope and Waterfall components.
InstrumentLab - Visual instruments and controls library.
BasicVideo - Basic video capture, playback and visualization library.
BasicAudio - Basic audio capture and playback library.
Free downloads:
OpenWire - Free Open Source library for creating property to property connections.
OpenWireEditor - OpenWire Editor Prerelease Technology Preview.
GDI+ - Free Open Source interface based Delphi friendly GDI+ library.
Free VCL components - Large amount of free C++ Builder and Delphi components.