You guys are in luck! There's a helpful chrome plug-in for that called WaxPost that allows users to easily crosspost an image from DA, FA, IB, or SF to Weasyl. A link is added on each supported site's page that allows quick and easy crossposting of individual images.
I'm, personally, looking forward to it because it'll help streamline my ability to maintain a presence on both sites :P
Link
zaisan
Neat :D