PSL stands for Pearson Specter Litt
Mike quotes A few good men in several parts and even quotes Tom Cruise to Jessica about her leading Mr. Forest right where he's dying to go right before Jessica does to Mr. Forest what Tom Cruises character did to Jack Nicholsons character in the movie.
D.B. Woodside (Jeff Malone) and Gina Torres (Jessica Pearson), who play lovers on this show, also played lovers in another TV series, 24 (2001).