Online sales, which hit the $100 billion mark just three years ago, will pass $200 billion, according to a study from Shop.org and Forrester Research. In fact, total sales (including travel) are seen as reaching $211.4 billion. Sales excluding travel will hit $138 billion.

In 2006, the largest non-travel categories are seen as computer hardware and software, which should hit $16.8 billion, followed by autos and auto parts, at $15.9 billion, and apparel, accessories and footwear ($13.8 billion).

Pet supplies and cosmetics and fragrances are seen as the categories with the highest potential: Each is foreseen as increasing by 30%.

Marketers are testing a variety of strategies to enhance their multichannel efforts. Nearly eight in ten are using consistent pricing strategies, and almost half are allowing customers to buy and redeem gift cards either online or in stores. One third enable consumers to earn loyalty program points across all channels, and more than one quarter offer in-store product information online.