There is a long list of potential SCOTUS nominees.
The two most mentioned candidates are Sonia Sotomayor and Diane Wood, each mentioned by all of the sources above. Next comes Elena Kagan, mentioned by six of seven. Ties are listed in no particular order.
Here they are:
-Sonia Sotomayor, 2nd Circuit appellate judge
-Diane Wood, 7th Circuit appellate judge nominated by Bill Clinton
-Elena Kagan, incoming U.S. solicitor general, served in the Clinton White House
-Michigan Gov. Jennifer Granholm, former federal prosecutor
-Kathleen Sullivan, former dean of Stanford Law School and former Harvard law professor
-Leah Ward Sears, chief justice of the Supreme Court of Georgia
-Kim McLane Wardlaw, 9th Circuit appellate judge nominated by Bill Clinton
-Massachusetts Gov. Deval Patrick, former assistant attorney general for civil rights under Bill Clinton
-Harold Hongju Koh, dean of Yale Law School, has been nominated by Obama to be legal adviser to the State Dept.
-Cass Sunstein, University of Chicago law professor
-Secretary of State Hillary Clinton
-Ann Claire Williams, 7th Circuit appellate judge originally nominated by Ronald Reagan, elevated to the Court of Appeals by Bill Clinton
-Sandra Lea Lynch, chief judge of the 1st Circuit Court of Appeals, nominated by Bill Clinton
-Johnnie B. Rawlinson, 9th Circuite appellate judge, nominated by Bill Clinton
-Ruben Castillo, district court judge for Northern Illinois, nominated by Bill Clinton, also would be first Hispanic Supreme Court justice
-Merrick B. Garland, DC Circuit appellate judge, nominated by Bill Clinton
-M. Margaret McKeown, 9th Circuit appellate judge, nominated by Bill Clinton
-Pamela Karlan, Stanford law professor
-Homeland Security Secretary Janet Napolitano
-Interior Secretary Ken Salazar
-Seth Waxman, former U.S. solicitor general, argued Boumediene v. Bush before the U.S. Supreme Court
-Teresa Wynn Roseborough, deputy assistant attorney general under Bill Clinton
-William Fletcher, 9th circuit appellate judge, nominated by Bill Clinton
Another mention: Jose Cabranes, appointed by Bill Clinton to the 2nd Circuit
http://politics.theatlantic.com/2009/05/souter_replacement_watch_master_list.php