Cloverfield

An effective homage to pretty much every sci-fi creature film made, with the added bonus of feeling like it was made for YouTube.
http://www.imdb.com/title/tt1060277/

Iron Man

The plot, actor, and special effects align. (Why not open this puppy on Memorial Day weekend and make a bigger bundle?)
http://www.imdb.com/title/tt0371746/

Lilja 4-ever

Despite the somewhat unbelievable set-up, quite powerful. Makes you understand how lucky you really are.
http://www.imdb.com/title/tt0300140/

Earth 2

Really not at all like Firefly, but engaging in its own sense. 22 episodes, what do you have to lose?
http://www.imdb.com/title/tt0108758/