This is the only rankings of LL.M.s by AUAP which I have just found. It looks interesting!!

2010 Rankings of American LL.M/Master of Law

1) Cornell University (NY)
2) University of Pennsylvania
3) NYU (NY)
4) Columbia University (NY)
5) Harvard University (MA)
6) Fordham (NY)
7) Boston U. (MA)
8) Duke University (NC)
9) Geroge Washington University (DC)
10) Cardozo Law School Yeshiva University (NY)
11) University of Chicago (IL)
12) Yale (CT)
13) American University (DC)
14) Pennsylvania State University (PA)
15) LSU (LA)
16) UCLA (CA)
17) University of Southern California (CA)
18) Washington University (MO)
19) University of San Diego (CA)
20) Georgetown Universtity* (DC).

this ranking is bullshit. it's just for their own marketing purposes, to promote their service.

All the rankings are for marketing purposes of the respective author...