Is that possible?

I think GHNS requires that a particular protocol be implemented on the server providing the data. So that would mean deviantart would need to implement the protocol. Further, those providing content would need to provide information about what the content is, which would also be mean going back and changing all existing content.

It might be possible for GHNS to write parsers that allow it to retrieve content linked from KDE-look.org to deviantart. But that would likely break if deviantart changes how their pages work.

A more likely approach would be a KIO slave that allows for browsing deviantart, but that would require deviantary provide an API for accessing their content. I don't know if this API exists or not.

So... Which providers are aviable out there?
The New hot stuff thing is a very nice touch from KDE, but i would like to use even more providers as well.

I don't think there are any providers besides the default ones.