The refining feature was allready there at teoma.com , a askjeeves acquired company. askjeeves acquired it in 2001, they are looking very late for adding this feature on their main site. The same thing has been applied by clusty.com there is diefference in the clustering of both.

I am also working on the same area as my M.E. project, my results are looking comparable with clusty, it is on testing phase. This definately improves the precision.