I have yet to play it for the first time, but talking about expansions...
Well I take it you already have the "invincible" expansion for it, and other then that there are no official expansions or any chance of them popping up.
However, when diving in old material, there was a minor addition in the first Bottled Lightning fan-zine that was free to download on the old site.
Since it was free, and is no longer available here, I don't think it can hurt to offer it as a download.
It adds a new species to use (the Lysiri), along with a new abbility (the battlecry) and their own racial weapon (The Lysiri circle Blade).
I do not know how many issues where published, if any after the first free issue, but it would be great if a new "fan-zine"like it would pop up to add new content for all the products of firefly.
Including land of ogg and faery tale.