Bing Webmaster Tools
Bing is Google's closest competitor with about 25.6 percent of organic searches in May 2012 compared to about 68.9 percent of organic searches for Google sites, according to trend tracking firm comScore.
Bing's Webmaster Tools suite gives site owners a second perspective and provides data about how the number two search engine is interacting with the owner's sites. The tool set makes it easy to learn which pages have been indexed and what keywords Bing located on the site.
Blekko SEO Tools
Site owners may also gain some insights from small or emerging search engines like Blekko. Blekko recently updated its SEO tool set and reports that its bot, Scoutjet, indexes something like 100 million web pages every day.
Any user can see how Blekko has interacted with a site by typing the site domain followed by a slash and the term “seo”.
This means that Blekko may be used to compare competitive sites and, potentially, gain insights that could lead to a competitive advantage.
Unfortunately, Blekko's results are not nearly as comprehensive as either Bing's or Google's.
Google, Bing, and Blekko are three search engines that offer SEO-related tools that may help site owners improve site traffic. Google and Bing both provide complete information about how each search engine is interacting with a verified site, while Blekko supplies less detailed information about any site, including competitors' sites.