I don't check Weasyl often, but I do post new submissions to it most of the time.
I made a new version of CrosspostSharp, my Windows art crossposting app.
It can load/save pictures from files (PNG, JPEG, GIF, or its own format) or load them from websites that you're logged into. It can also post to most of those websites, and it gives you specific options for each.
It can also post to FurAffinity or Weasyl if you install Java and use efc.jar.
Let me know on DeviantArt or FurAffinity (@lizard-socks) if there are any features you'd like to see added.