BoltBait's Skew Plugin v1.0
Once installed, find Skew Horizontal and Skew Vertical in the Effects > Distort menu:
Skew Vertical pretty much looks the same.
Download:
Until I add this to my latest plugin pack, you can download it here...
Skew.zip
To install this plugin, download skew.zip to your desktop, unzip all files to your desktop, and run the Install_Skew.bat file to install the Skew.dll file to your Paint.NET Effects directory.
Source Code:
Enjoy. 😎