His most famous works include the theme to Summer of '42 and "Windmills of Your Mind," from the film The Thomas Crown Affair. From Youtube clips, Summer here, Windmills here.
Personal favorites of mine are the haunting theme and variations from "The Go-Between" and the whole soundtrack of the not-well-known "Young Girls of Rochefort."
Memories
When I was in the Stanford MD-PhD program, around 1984 I was working late in the lab and the classical FM station was on. The theme of "The Go-Between" was played, and I either wrote down the name or may have even called the station to find out what it was. Theme and variations here.
When we lived in Chicago 1997-2002, there was a screening of the semi-forgotten film "Young Girls of Rochefort," which got a stellar review from the free weekly, Chicago Weekly, in November 1998, here. I saw it, dragged my wife to it the next night, and got a DVD a few years later when they became available. The songs in Young Girls are diverse but try one or two; the song of Maxence, here; the art store here.
Footnote
See the opening minutes and closing minutes of Summer of 42, here and here. (Unrelated to music, the Summer of 42 pharmacy scene here, with priceless character actor Lou Frizzel, see also here.)
