All of the major search engine have special pages for advanced searching, i.e. forms that let you target your searchers more precisely by filtering out specific search query terms or types of files and webpages. A few of them, AltaVista, HotBot and AOL included, let you build true Boolean search queries.
Search.com lets you search a lot of specialized search sites. Use the pull down menu to select search type (email, shopping, jobs, music, software etc.).