Getting started with practical web accessibility, section 2 Demonstration: an analysis of a page:

Rule 7: Alternatives to forms

The page contains only one form, a site search form. Such a form normally does not need a particular alternative, but it should be accompanied with a link to help on the form and to contact information. There is no such link here. There is a link named “Search” but it is among the last set of navigational links and rather unnoticeable. Moreover, the link actually points to the “Advanced search” page. That page contains the link “Advanced search tips,” but it points to a page on the Google site; the search apparently uses Google technology. Thus, there is really no answer to a potential user’s question what to do if he fails in trying to use the search form.