Here's a great clip of the incomparable Olivia Adams, provided by Jerry over at the-female-orgasm.com.
Every time I watch a clip of Olivia I'm impressed by her patience and finesse. This clip is no exception. She gradually brings herself to an orgasm with powerful, visible contractions @ 7:45, preceded by a few pre-orgasmic contractions. Naturally while oozing her trademark quantity of lubrication.