A Taxonomy of Site Search by Tony Russell-Rose.
From the post:
Here are the slides from the talk I gave at Enterprise Search Europe last week on A Taxonomy of Site Search. This talk extends and validates the taxonomy of information search strategies (aka ‘search modes’) presented at last year’s event, and reviews some of their implications for design. But this year we looked specifically at site search rather than enterprise search, and explored the key differences in user needs and behaviours between the two domains. [see Tony’s post for the slides]
There is a lot to be learned (and put to use) from investigations of search behavior.