Most of mine have already been mentioned:
Mark and Karen's AT: pure intensity, the first (possibly only) time he 100% 'sold' a dance. Everything came togther perfectly: the mood, the music, the choreography and the quality of dancing.
Tom and Camilla's showdance: especially coming after what had gone before! Summed Tom up perfectly, he was all about the Hollywood/showman/tap/Fred Astaire vibe. I switched my vote to him in that year's final after that dance.
Kelly and Brendan's AS: who cares about an illegal lift? One of the best dances of all-time for me and my favourite AS by miles. She oozed pure Hollywood glamour throughout.
Chris and Ola's Charleston: it was the first ever Charleston, it suited him down to the ground (which admittedly wasn't very far in his case

), Ola looked gorgeous, I loved the song and the 'swimming' bit at the end. Not the most technically perfect dance but pure entertainment.
Lisa and Brendan's VW: no-one choreographs a VW like Brendan and this was beautiful from beginning to end.
The opening few bars of Alesha and Matthew's cha cha: just something about that moment when she flung her head back and her arms up proudly in a "I own this dancefloor" way to the first blaring horns of Beyonce's "Crazy in Love". The rest of the dance didn't quite live up to the beginning but it was the moment I started to see her as the winner.
And a pro one - Katya and Pasha's jive/quickstep to Caro Emerald singing "That Man". One of the fastest jives I've ever seen, and a glimpse of what Katya might have done if she'd ever been given a genuine contender.