Reese Witherspoon's recent appearance on our list of the sexiest dresses from this year's Oscars had us thinking . . . is she a secret siren? America's sweetheart has certainly had some sultry looks along the way, starting with some dresses way back in the mid-'90s. Instead of charting all of her red carpet glamour, we're zeroing in on the most sizzle-worthy dresses of all.