Forrester Research recently forecasted ecommerce revenues in coming years, painting a picture of slowing growth. Forrester sees the online retailing space adding a steady $30 billion in sales every year for the next five years. In percentage terms, that represents a flatter growth curve than the past several years, when annual growth rates generally exceeded 25% a year.

According to Forrester, 2007 online retail sales reached $175 billion, a 21% increase over 2006.

Here are the firm's forecasts for ecommerce revenues:

2008: $204 billion, up 17%
2009: $235 billion, up 15%
2010: $268 billion, up 14%
2011: $301 billion, up 12%
2012: $335 billion, up 11%

As obstacles to online retail sales growth, Forrester pointed to some advantages of brick-and-mortar shopping, like its social aspect, and the ability to see, touch and try items. Forrester also identified the highly targeted nature of online shopping (which it called "spear-fishing") as a limiting factor for ecommerce revenue.