DrumGizmo is an open source cross-platform drum plugin and stand-alone application. It is comparable to several commercial drum plugin products.
Stand-alone, Lv2 and VSTi versions available
Open drumkit file format, allowing the community to create their own drumkits
Drum velocity, allowing for several different hit velocities for each drum
Multichannel output, making it possible to mix it just the way you would a real drumkit
Optional built-in humanizer, analyzing the midi notes, adjusting velocities on-the-fly
Stand-alone midi renderer, generating .wav files, 1 for each channel
Stand-alone midi input, making it possible to use DrumGizmo as a software sampler for an electronic drumkit