NeedleSearch lets you bookmark the search engines of your choice. Because of the easy and powerful Auto-add functionality NeedleSearch not only lets you bookmark this big search engines like Google or Yahoo, but also the search engines for which no toolbar exists.
Besides this you can launch a multifield search as well. This means that you can i.e. enter name & city for a phone directory with just one search.
The NeedleSearch Toolbar is an excellent tool for the advanced user of search engines.