I had something like that setup on a previous website – when you rated a film you could then update your Facebook or Twitter I think. I might take a look into writing this as a plugin, but this would be my first stab at writing one… It would be really nice if it did link into your plugin tho, so that you could ultimately set it up so that it would either only recommend on the site itself, or if you could choose to link it in with the social media platforms which you use too.
