For me it was Justine Henin adding to her Grand Slam titles and then winning the Year End Championships for the 2nd year in a row. Her dominance at Roland Garros (4 titles in 5 years) is just incredible and her triumph at the US Open, after beating both Williams Sisters on the way, just fantastic. Marion Bartoli's run to the Wimbledon final was a joy too, I couldn't believe her Semi final win over Justine after she was hammered in Eastbourne a few weeks earlier. (Justine MUST win Wimbledon at some stage- surely!!!)
Have to mention the great Roger Federer of course. Amazing to win 5 Wimbledons in a row, what a Final against Nadal. As you can guess from above, I usually watch the WTA tour but I absolutely loved the men's final this year.
Can't wait for the Australian Open next week!!!!