Midnight, along with the rest of the 10th doctor, is on Netflix.

Anyways, my two favourite episodes are currently Midnight, because HOLY SHITFUCK THATS WEIRD.
And the waters of Mars. 'I am Time Lord Victorious!' 'We aren't just fighting the flood, we're fighting time itself. [i]And I'm going to win!'[/i] it's a fixed point in time.