Everyone knows that Google is the 800-pound gorilla amongst search engines, so much so that you’ll hear “google” being used as a verb in casual conversation. But even with Google’s search dominance there is still a significant portion of search activity happening on other engines.

According to Hitwise’s April 2008 search share numbers (see chart) Google has a firm grasp on the majority of search traffic with just over two-thirds of all searches being conducted on Google. However, their 67.9% share of searches also means that there are still 32.1% of searches happening somewhere else. From a search engine marketing standpoint this just means that it’s important to diversify your search engine marketing efforts across search engines.

At a minimum, at least target Google and Yahoo, combined they cover 88.18% of searches, and also cover a wider range of demographics since each engine tends to attract a different type of user. One other note, even though MSN and Ask.com have relatively low numbers, there still make be great ROI in targeting those engines, especially since many of your competitors will be ignoring them.