TechPowerUp checked out the Zaunkoenig M2K Gaming Mouse
A quote from the article:
Exclusively intended for fingertip grip, the 24 g Zaunkoenig M2K is the world's lightest gaming mouse. With a carbon fiber body, Japanese Omron main button switches, and driverless 8000 Hz polling rate, the M2K is built for the lowest latency possible without compromising on anything.Zaunkoenig M2K Gaming Mouse Review