Ann Smarty at Search Engine Journal has a good compilation of sites that let users compare the search results from major search engines. With online advertising taking off, this is one list of tools that will be of great help for search engine optimization of content.

The meta search engines are a great way to actually compare results from various engines. It is becoming more and more doubtful if any new search engine will come to overtake any of the present majors - Google, Yahoo and Microsoft's Live. Hence, there are expectations for more engines that are based on the results of these engines and giving users more flexibility in viewing the results from all engines in one place.