The related search is getting common these days, as every major search engine is refining to precisely define what you want to find. Yahoo displays them both at the top and at the bottom of the page, while Ask has an entire sidebar for search suggestions. Clusty aggregates results from other search engines and clusters them dynamically.
Google was more conservative and placed the related searches at the bottom of the page and sometimes in the middle of the page as an "inline revision", but now it started to show the queries at the top of the page. Usually the related searches add one or two words that disambiguate the query. They're also useful as a guidance if you don't know too much about a certain domain and you want to explore it.Google, Search, Web Search, Google Search, Search Engine, Related Serarch