I love Firefly. I have the series and Serenity on DVD, and keep meaning to get the Blu-rays.
Great cast, and always good seeing them star or guest-star in other things (Fillion in Castle, Baldwin in Chuck, Staite in Atlantis, Baccarin in SG-1 & V, Tudyk in Dollhouse, etc.). Pity about the "Curse of Summer Glau" though of course!
There was even an episode of Castle where the main character Richard Castle (played by Fillion) dressed as Mal for a Halloween party. Excellent little in-joke / reference.
Morena Baccarin is utterly stunning, and my no.1 "Sci-Fi / Cult TV babe".
Now I'm near the end of my "complete Stargate marathon", I'll probably watch Firefly again.