Are there any helicopters with ejection seats?
Many years ago I read about the Kamov-50 helicopter family* being the first helicopters equipped with ejection seats. And Wikipedia verifies my memory:


  It is the world's first operational helicopter with a rescue ejection system, which allows the pilot to escape at all altitudes and speeds.


In the same article for the same helicopter it is mentioned that


  Before the rocket in the ejection seat deploys, the rotor blades are blown away by explosive charges in the rotor disc and the canopy is jettisoned.


Also, if you want to count experimental helicopters in, Sikorsky S-72 RSRA may be another one. Here is an interesting video, demonstrating the blades being blown away, and ejection of the pilots.



As a side note, in the article I read in an aviation magazine many years ago, it mentioned a synchronization of the seat with the blade rotation so that the seat passes between the blades. It was based on a working principle similar to the middle machine gun that some WW2 German airplanes were equipped with that fired the projectiles between the propeller blades.

Judging from the fact that I read it somewhere in the late 90s where the project was still new and developing, as PlasmaHH pointed out, that was probably more a thought rather than a fact.

* Kamov 50 and its variants/successors like Ka52