Firefly only lasted one season before Fox cancelled it. It did have a follow-on movie though called Serenity (zing did mention this above
).
Definitely worth watching though. As gaz said, it's more of a Western in ways anyway than a SciFi series.
I think we need to get back to the topic though, before this turns into a Nathan Fillion Appreciation Thread
(although of course posts about Captain Mal or Richard Castle are on-topic
)