Look at your target school on lawschoolnumbers.com I cant say how accurate it is but im sure it will still give you some idea about what your chances are at top 20 school. http://lawschoolnumbers.com/
I think it's accurate-ish. I like to use the mylsn.info one a little more, because I like being able to click through and check out the relevant LSN profiles and see scholarship money awarded.