Freeware : Plug-Ins Hosts for Mac

All Mac Win AU Lab by Apple            Audio Unit host included with Tiger Xcode Tools   HostX by Mitchell Turner            Free-Standing VSTi host   Kil2 by Fredrik Olofsson            VST Host   MissWatson by Teragon Audio            command-line AU or VST host   MultiVST Shell by The Lone Roger            VST instruments host   Ouroboros by Illposed Software            sample player that hosts AudioUnits   SynthTest by Creed            AudioUnit Effect Selector   Toontrack Solo by Toontrack            Toontrack samplers host   Ugly VSTi interface by ReFuse Software            VSTi Host