The little-known search operator has customized its software for mobile devices, joining many big players in the ever-growing mobile search market A little-known search engine has optimized its offering for mobile devices, joining an increasingly crowded market of services targeting cell phone users.Clusty’s mobile service returns search results for mobile users much like it does on computers, but once users click on a search result, they can see the difference. Clusty optimizes Web sites for mobile phones, displaying pages to fit in the small screen of the phone and stripping out images that wouldn’t look good on a mobile, said Raul Valdes-Perez, CEO of Vivisimo, the company that runs Clusty.The Web sites are filtered through Clusty servers, where software does the optimization before displaying them on the phone, he said. The process is reminiscent of one that Opera Software ASA uses with its Opera Mini browser. The Opera Mini browser works in conjunction with Opera’s backend servers that strip down sites for better viewing on mobile devices. Like Clusty’s PC search, its mobile search displays categories of search returns in addition to regular results. A search for Seattle, for example, returns such categories as arts, real estate, University of Washington, and Puget Sound. Each category contains different relevant sites.The mobile Clusty has an additional feature as well. At the bottom of the page, users will see refined queries, which are related queries that users can choose to click on rather than having to type in another search. In the Seattle example, the refined search terms included City of Seattle, Seattle Mariners, and Seattle University. Clicking on one of those terms will return results as if the term were typed in the search box.Clusty joins a variety of companies in the mobile search market. The big names in computer-based search, such as Google, Yahoo, Microsoft, AOL, and Ask.com, all offer mobile search services. In addition, companies like Medio Systems, InfoSpace, and JumpTap develop technologies that can be used by other companies, such as mobile operators, to offer self-branded mobile search. Clusty search works by combining search results of other services and also crawling parts of the Web itself.Clusty’s creator, Vivisimo, also provides search services for government agencies, including the U.S. National Library of Medicine, as well as enterprises. It recently introduced technology that lets users of BlackBerrys and PDAs search corporate intranets. Technology IndustrySoftware DevelopmentSmall and Medium Business