Richard Dawkins' site has links to a great many debates between atheists and apologists, and not just the ones the atheist clearly wins either.
Apart from that, I recommend searching YouTube for "debate" and the names of famous atheists and/or apologists. May I suggest Richard Dawkins, Sam Harris, Christopher Hitchens, Michael Shermer and Daniel Dennett on one side, and Dinesh D'Souza, William Lane Craig and Alister McGrath on the other. I won't comment on the relative abilities of these folks, but they've each been in a lot of debates.
- SmartLX