Ward Cunningham talked about eXtreme Programming, I liked too much this talk because he was capable to change and correlate so disperse topics as OO, DesignPatterns, WikiWikiWeb and XP naturally.
The name of the presentation is: "System of Names", so he started talking about the importance of the names because people assume behavior based on names. Of course, choosing the right name is pretty difficult, so a thesaurus can help with this task.
Ward suggest that we should revise the names choosen in a system, so they reflect the ultimate "roles", and we should try to find names consistently with the metaphor. If you need a name that does not exists, create it. This is what patterns are about.
Once patterns and names are introduced, he talked about HyperCards and CRCCards, more info about this on: http://c2.com/doc/firstcrc.pdf
He also mention the effectiveness of PairProgramming, and the importance of the programming rythm, and how you should divide your development in episdes.
One metaphor I liked so much was the skiing metaphor http://c2.com/cgi/wiki?EverythingAboutObjects
Another pretty good metaphor was:
Manage Complexity as a Debt
Skip Design = Borrowed Money
Maintenance Headache = Internet Payments
Refactoring = Debt Payment
Engineering Policy = Financial Policy
I liked bery much this talk, I think it was the first time I saw anybody talking about XP whit this clarity of ideas.