With so many more people heading to the internet when doing their shopping, retailers are finding that they need to boost their search engine optimization (SEO) to reach customers, but a new report finds that there is still a lot of work to be done from retailers in getting the top spots for a number of keywords.

According to the 2010 Search Marketing Guide from Internet Retailer, retailers owned the top three search results for only a little more than half of 20 top merchandising categories. Of the 60 possible top spots, retailers held 35 – up from 29 in last year’s study.

The report finds that some retailers are doing better than others with their search engine optimization (SEO) results and that the ones that are succeeding are generally using analytics to help figure out the right keywords to use.

It might not be surprising that the retailers who were born out of the boom in internet shopping are doing the best in search engine optimization. The study finds that Amazon.com came up 11 times in the top 60 keywords while Overstock.com came up three times. No other retailers came up more than once.

These retailers might see their rankings change if Google switches to Caffeine anytime soon. Recently 360i compared 40 retail keywords in Caffeine and "Decaf" versions of Google and found that there was a 15 percent shift in first page rankings.