City on the Edge of Forever also has gotten a lot of votes! In fact, it and Amok Time are the two biggest winners (Mirror, Mirror is third). I'm a little alarmed to see that City was written by Harlan Ellison, but I will work through it.

I'm beginning to believe I shall be the last person on the planet to see XI. I've got the Netflix DVD sitting on my desk, but no will to watch.

All I can say is that I found it deeply, deeply awesome. (Also, if even I have seen something, you may well be in contention for the honorable title of Last to See.)