The concatenative real-time sound synthesis system CataRT plays grains from a large corpus of segmented and descriptor-analysed sounds according to proximity to a target position in the descriptor space. This can be seen as a content-based extension to granular synthesis providing direct access to specific sound characteristics.
The current CataRT comes in three flavours:
Of historical interest is the original CataRT classic, a modular patch system for Max/MSP based on the FTM&Co. extensions (for Mac and Windows)