The Ancestry.com Blog has a new article that describes a feature to be implemented soon: a sliding control to quickly broaden or narrow your search results. Quoting from the article:
Don’t see the search results you were expecting? Simply drag one or more sliders from left to right to quickly modify your results. The slider position shows how closely your search terms should be matched. With all the sliders to the left, your results are matched at the broadest level, and moving one or more sliders to the right will display more exact matches.
You can read the full article and see screenshots of the new sliding control at http://goo.gl/02qvH5.