Kontakt - With KONTAKT 6, you can sound like a snare drum, a symphony orchestra, or anything in between, from a universe of sampled instruments.
ZynAddSubFX - ZynAddSubFX is an open source software synthesizer for Linux, Mac OS X and Microsoft Windows.
UVI Falcon - Sampler/synth hybrid instrument
Qsynth - Qsynth is a simple Qt4 application wrapper for the ...
Magix Independence Free - Magix Independence Free is a sampler software that allows you to create any type of sound with its 2Gb library.
Surge XT - Open-source subtractive-hybrid synthesizer formerly sold commercially as Vember Audio Surge.