1. Dan Goldstein is a behavioural economist and principal researcher at Microsoft Research. His recent research includes several applications of behavioural research in online business applications http://www.dangoldstein.com/cv.html
2. Work of Cormac Herley, while possibly not best described as behavioural economics, has many examples of clever research on incentives and screening in online e-commerce environments http://research.microsoft.com/en-us/people/cormac/ Most recent work on Nigerian scammers is summarised here http://online.wsj.com/article/SB10000872396390443931404577548813973954518.html
3. UK Cabinet Office document MyData outlines a major approach to utilising people's online information to provide them with better recommendations for deals. http://www.cabinetoffice.gov.uk/resource-library/better-choices-better-deals/
4. Russell Sage Foundation's general reading list on behavioural economics has some useful material. A list of TED Talks here Ian Ayres talk on "Carrots and Sticks: Unlock the Power of Incentives to Get Things Done" gives many examples of behavioural principles in action in online business.