Offering unique features and first-rate service, Amazon.com continues to rule the Books category in the latest PowerRankings announced today by Forrester Research, Inc. (Nasdaq: FORR). Forrester PowerRankings combine survey data from online consumers and unbiased shopping tests to provide objective rankings of the leading eCommerce sites. The companies following Amazon.com were Borders.com, barnesandnoble.com, and buy.com.

Amazon.com retained its title as top online bookseller with consistently low prices, solid customer service, and innovative features like automated recommendations. A wealth of customer, staff, and expert reviews, as well as quick delivery and a simple return process, kept Amazon.com ahead of the competition.

“Amazon.com started the online book-buying frenzy, and it has never lost its lead,” said Tom Rhinelander, senior analyst at Forrester. “Borders.com and barnesandnoble.com are in a heated battle for the runner-up spot, but both have a lot of work to do to contend with the category heavyweight Amazon.”

With a high score in the transaction category, Borders.com came in second place, offering optional registration and real-time inventory information. Shoppers appreciated its exceptional call center responsiveness, but low scores in ease-of-use and site reliability kept the site behind the leader. Coming in a close third, barnesandnoble.com provided notable search engine capabilities and implemented a simple return process. However, poor call center services and mandatory registration left consumers frustrated.

Although buy.com offered low prices and speedy delivery, long telephone holds for customer service and a lack of basic features landed the site in fifth place. Instant email responses and an always-open call center haven’t been enough to keep consumers from complaining about the site’s lack of content.

For the updated PowerRankings, Forrester surveyed 19,000 consumers from Greenfield Online’s 400,000-person online panel to identify the most popular eCommerce sites. A team of Forrester shoppers then evaluated the shopping experience for these sites by performing a series of rigorous tests in six areas. The consumer data and Forrester shopper scores were then synthesized and weighted, with consumer views accounting for two-thirds of the overall PowerRanking. A complete set of PowerRankings results are made available to all ranked companies.

In the coming weeks, Forrester will be announcing results in additional PowerRankings categories, including Apparel, Brokerage, Computing, Flowers, Health, and Toys & Games. Additional information about each of the categories, including a complete set of rankings and scores, can be found at the PowerRankings Web site — powerrankings.forrester.com.