Jeff Barr gave a presentation on Amazon Web Services and how developers can use them to build scalable web applications. He discussed Amazon's EC2, S3, and SQS services. EC2 provides virtual servers, S3 provides storage, and SQS provides message queuing. He gave examples of how companies like GigaVox Media have used these services to reduce costs and improve scalability compared to managing their own infrastructure. Barr concluded by taking questions and providing resources for learning more about AWS.