Lost
I just finished the last episode of season two. Official Site. Fan Site.
This show is very well done. The director(s) should be commended. The story is very good. I like the interwoven story lines. I watched this in a weekend marathon. Both seasons. One after the other. Let me tell you, I was paranoid and fascinated by the final twist. Flawed heroes. X-Files in the jungle feel. I felt the desperation. It has been a long time since I teared up while watching a TV show.
I love the visual control this show has. One of the characters had to leave the camp. When he came back, the first member of the group that sees him is his dog. They have a reunion on the beach and you just know the dog is happy to have his master back.
The people one the island know there is something wrong. They know the island has secrets. The new island dwellers know there is little they can do to stop the island and the "others" from doing whatever it is they will.
I highly recommend the series. If you can swing it, watch them several at a time.