My (biased) favorite was 2005 Einstein SF2-3. With 1 second left, 503 capped a tetra breaking up a row (13 point swing). We won by 13 points.
http://www.youtube.com/watch?v=wFBQdQXIuwY (the real time score was incorrect towards the end of the match as red owned one more goal then shown).
The match before it, we won by 3 points, so the combined winning margin was 2 tetras.