Check out the Net Usage Index for Retail by Akamai.

The Net Usage Index for Retail enables users to monitor the world's online retail habits 24 x 7, providing real-time insight into the trend of consumers increasing their share of spending on the Web. The Index features:

• Aggregate, real-time visitors per minute for a representative set of more than 270 global retail/e-commerce sites
• E-commerce traffic levels by continent over a 24-hour period
• Historical data on e-commerce growth and spikes by geography

[Via The ShiSh List]