FileInfo.com - The File Extensions Resource

.VST File Extension

File Type 1	Targa Bitmap Image (Most common)
File Format	File
Common?	No
File Description	Raster image based on the Targa Truevision format; can store data up to 32 bits per pixel, with 24 bits for the RGB information and 8 bits for the alpha channel; may also incorporate lossless RLE compression to reduce the file size. Targa image files most often use the .TGA file extension.
Program(s) that open vst files	Mac: Adobe Photoshop; Adobe Photoshop Elements for Mac Windows: Adobe Photoshop; Adobe Photoshop Elements

File Type 2	Visio Drawing Template
File Format	File
Common?	No
File Description	Template for creating a new drawing with Microsoft Visio; used for building flowcharts and other organizational drawings.
Program(s) that open vst files	Windows: Microsoft Visio

File Type 3	VST Audio Plugin
File Format	Standard File
Common?	No
File Description	File or folder containing a VST (Virtual Studio Technology) plugin; used for creating or modeling audio effects; typically used by digital audio programs to modify recorded sounds.
Program(s) that open vst files	Mac: Steinberg Cubase software; Audacity with VST Enabler Windows: Steinberg Cubase software; Audacity with VST Enabler; Image-Line FL Studio Unix: Audacity with VST Enabler

Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/vst