Honestly, I think it would be more for image analysis then for artistic uses. Though, it can help to find edges ... and that could prove useful, I suppose.
Some effects are detailed here:
http://www.getpaint.net/doc/latest/en/EffectsMenu.html
And briefly here:
http://en.wikibooks.org/wiki/Paint.NET/ ... dge_Detect
I don't know if there is one, but if not, someone should write a detailed page about various effects, how they work, what they do, user interface details, and what they can be used for. I would, if I understood it all. Maybe I will...