From NeOn Wiki
The functionality of the NeOn Toolkit can be easily extended with powerful plugins in the following categories: <ask> </ask>.
You can learn how to install new plug-ins by viewing this instructional video.
Here is a list of all available plugins. There's also a list of known issues
Plugins for NTK2.5 (OWL API)
Plugins for NTK2.4 (OWL API)
Plugins for NTK2.3.2 (OWL API)
Plugins for NTK2.3.1 (OWL API)