Specimen is an open source, MIDI controllable audio sampler. Features include:

 - Up to 64 patches with 8 notes of polyphony each
 - Fast, high quality pitch scaling
 - Linear ADSR volume envelopes
 - MIDI/jack-transport syncable LFOs
 - Low pass filter with resonance
 - A variety of direction-independent playback modes
 - A zoomable sample editor for loop and play points
 - Portamento

WWW: http://zhevny.com/specimen/