Some bedtime reading, courtesy of a bout of surfing at CiteSeer:

• Keep Your Options Open:
  Extreme Programming and Economics of Flexibility
• Scaling The Management Of Extreme Programming Projects
• No Pain, No XP Observations on Teaching and Mentoring Extreme
  Programming to University Students
• Value of Commercial Software Development
  under Technology Risk
• Retrofitting unit tests
• Automatically Generating System Mock Objects
• Distributed eXtreme Programming
• The XP of TAO – eXtreme Programming of Large, Open-source Frameworks
• Program Comprehension Risks and Opportunities in Extreme
  Programming
• EasyMock: Dynamic Mock Objects for JUnit
• Knowledge Sharing: Agile Methods vs. Tayloristic Methods
• Do we need ‘agile’ Software Development Tools?
• XP + AOP = Better Software?
• eXtreme Programming in Open-Source and
  Distributed Environments
• Leveraging Open-Source Communities
  To Improve the Quality & Performance of
  Open-Source Software
• Empirical Findings in Agile Methods
• Distributed Pair Programming:
  Empirical Studies and Supporting Environments
• Perceptions of Agile Practices: A Student Survey
• Supporting Distributed Extreme Programming
• Knowledge Management Support for
  Distributed Agile Software Processes

All the papers listed above were found from CiteSeer’s links from a single initial page.