I don't think the term "plugin" is perfectly defined. Or at least, I am unsure exactly what types of "plugin" you are asking about. But I think you might be referring to a couple things:
LabVIEW Add-ons: Add-ons are code that you can re-use. Some are free. Some must be purchased. They are available via the LabVIEW Tools Network.
Toolkits: NI provides lots of extra toolkits that can be purchased for LabVIEW. See here.
Plug-in architecture: Or the concept of a "plugin" as a programming technique is explained here.
http://www.medicollector.com
