I don't know if this has been posted before, but it is the first time I have seen this: Refine results. I wonder if this is due to the new ask.com interface.
I haven't seen it before. http://www.google.com/search?q=celiac+disease brings it up as well. Have you seen it before, Mong? Is this not new?
This looks like something to do with the new Co-op feature of Google. I haven't had much time to see what it's about though, so I'm taking a wild guess here.
Searching for Major Cities also lets you refine your searches (Logdings, Dining, Attractions, etc) Searching for diseases will let you refine for treatement, symptoms, test/diagnosis etc. I would not be surprised if they do/did provide (now or in the future) frequently executed "subseareaches" as refinements to you initial search NOTE: if a search is "keyword1" then "keyword1 keyword2" is a subsearch of the first search Well the more: operator added in refined searches is not explained in G's search operators http://www.google.com/intl/en/help/operators.html