Photographer Richard Prince took photographs of the 57 girlfriends Jerry Seinfeld had on the show and turned it in to the below composite.
See also Jason Salavon's work. (via @sippey)
Update: Max points out I may have misread the article and these 57 girlfriends are not necessarily Jerry's only. Supporting this is Sarah Silverman's inclusion in the composite even though she's was a love interest of Kramer's.